diff --git a/doc/source/launchers.rst b/doc/source/launchers.rst
index c799291..b95354f 100644
--- a/doc/source/launchers.rst
+++ b/doc/source/launchers.rst
@@ -78,6 +78,10 @@
   The target branch for the change that triggered this build.
 **ZUUL_CHANGE**
   The Gerrit change ID for the change that triggered this build.
+**ZUUL_CHANGES**
+  A caret character separated list of the changes upon which this build
+  is dependent upon in the form of a colon character separated list
+  consisting of project name, target branch, and revision ref.
 **ZUUL_CHANGE_IDS**
   All of the Gerrit change IDs that are included in this build (useful
   when the DependentPipelineManager combines changes for testing).
diff --git a/doc/source/zuul.rst b/doc/source/zuul.rst
index 7a10ca9..6c77477 100644
--- a/doc/source/zuul.rst
+++ b/doc/source/zuul.rst
@@ -809,6 +809,47 @@
   file patterns listed here.  This field is treated as a regular
   expression and multiple expressions may be listed.
 
+**skip-if (optional)**
+
+  This job should not be run if all the patterns specified by the
+  optional fields listed below match on their targets.  When multiple
+  sets of parameters are provided, this job will be skipped if any set
+  matches.  For example: ::
+
+    jobs:
+      - name: check-tempest-dsvm-neutron
+        skip-if:
+          - project: ^openstack/neutron$
+            branch: ^stable/juno$
+            all-files-match-any:
+              - ^neutron/tests/.*$
+              - ^tools/.*$
+          - all-files-match-any:
+              - ^doc/.*$
+              - ^.*\.rst$
+
+  With this configuration, the job would be skipped for a neutron
+  patchset for the stable/juno branch provided that every file in the
+  change matched at least one of the specified file regexes.  The job
+  will also be skipped for any patchset that modified only the doc
+  tree or rst files.
+
+  *project* (optional)
+    The regular expression to match against the project of the change.
+
+  *branch* (optional)
+    The regular expression to match against the branch or ref of the
+    change.
+
+  *all-files-match-any* (optional)
+    A list of regular expressions intended to match the files involved
+    in the change.  This parameter will be considered matching a
+    change only if all files in a change match at least one of these
+    expressions.
+
+    The pattern for '/COMMIT_MSG' is always matched on and does not
+    have to be included.
+
 **voting (optional)**
   Boolean value (``true`` or ``false``) that indicates whatever
   a job is voting or not.  Default: ``true``.
@@ -1051,13 +1092,11 @@
 If you need to abort Zuul and intend to manually requeue changes for
 jobs which were running in its pipelines, prior to terminating you can
 use the zuul-changes.py tool script to simplify the process. For
-example, this would give you a list of Gerrit commands to reverify or
-recheck changes for the gate and check pipelines respectively::
+example, this would give you a list of zuul-enqueue commands to requeue
+changes for the gate and check pipelines respectively::
 
-  ./tools/zuul-changes.py --review-host=review.openstack.org \
-      http://zuul.openstack.org/ gate 'reverify'
-  ./tools/zuul-changes.py --review-host=review.openstack.org \
-      http://zuul.openstack.org/ check 'recheck'
+  ./tools/zuul-changes.py http://zuul.openstack.org/ gate
+  ./tools/zuul-changes.py http://zuul.openstack.org/ check
 
 If you send a SIGUSR2 to the zuul-server process, or the forked process
 that runs the Gearman daemon, Zuul will dump a stack trace for each
diff --git a/etc/status/.gitignore b/etc/status/.gitignore
index 1ecdbed..218f297 100644
--- a/etc/status/.gitignore
+++ b/etc/status/.gitignore
@@ -1,4 +1 @@
-public_html/jquery.min.js
-public_html/jquery-visibility.js
-public_html/bootstrap
-public_html/jquery.graphite.js
+public_html/lib
diff --git a/etc/status/fetch-dependencies.sh b/etc/status/fetch-dependencies.sh
index b31d0de..ccaf74c 100755
--- a/etc/status/fetch-dependencies.sh
+++ b/etc/status/fetch-dependencies.sh
@@ -1,21 +1,23 @@
 #!/bin/bash
 BASE_DIR=$(cd $(dirname $0); pwd)
-echo "Destination: $BASE_DIR/public_html"
+DEST_DIR=$BASE_DIR/public_html/lib
+mkdir -p $DEST_DIR
+echo "Destination: $DEST_DIR"
 
 echo "Fetching jquery.min.js..."
-curl -L --silent http://code.jquery.com/jquery.min.js > $BASE_DIR/public_html/jquery.min.js
+curl -L --silent http://code.jquery.com/jquery.min.js > $DEST_DIR/jquery.min.js
 
 echo "Fetching jquery-visibility.min.js..."
-curl -L --silent https://raw.githubusercontent.com/mathiasbynens/jquery-visibility/master/jquery-visibility.js > $BASE_DIR/public_html/jquery-visibility.js
+curl -L --silent https://raw.githubusercontent.com/mathiasbynens/jquery-visibility/master/jquery-visibility.js > $DEST_DIR/jquery-visibility.js
 
 echo "Fetching jquery.graphite.js..."
 curl -L --silent https://github.com/prestontimmons/graphitejs/archive/master.zip > jquery-graphite.zip
-unzip -q -o jquery-graphite.zip -d $BASE_DIR/public_html/
-mv $BASE_DIR/public_html/graphitejs-master/jquery.graphite.js $BASE_DIR/public_html/
-rm -R jquery-graphite.zip $BASE_DIR/public_html/graphitejs-master
+unzip -q -o jquery-graphite.zip -d $DEST_DIR/
+mv $DEST_DIR/graphitejs-master/jquery.graphite.js $DEST_DIR/
+rm -R jquery-graphite.zip $DEST_DIR/graphitejs-master
 
 echo "Fetching bootstrap..."
 curl -L --silent https://github.com/twbs/bootstrap/releases/download/v3.1.1/bootstrap-3.1.1-dist.zip > bootstrap.zip
-unzip -q -o bootstrap.zip -d $BASE_DIR/public_html/
-mv $BASE_DIR/public_html/bootstrap-3.1.1-dist $BASE_DIR/public_html/bootstrap
+unzip -q -o bootstrap.zip -d $DEST_DIR/
+mv $DEST_DIR/bootstrap-3.1.1-dist $DEST_DIR/bootstrap
 rm bootstrap.zip
diff --git a/etc/status/public_html/index.html b/etc/status/public_html/index.html
index 3bd7a12..97025a6 100644
--- a/etc/status/public_html/index.html
+++ b/etc/status/public_html/index.html
@@ -19,16 +19,14 @@
 <html dir="ltr" lang="en">
 <head>
     <title>Zuul Status</title>
-    <link rel="stylesheet" href="bootstrap/css/bootstrap.min.css">
+    <link rel="stylesheet" href="lib/bootstrap/css/bootstrap.min.css">
     <link rel="stylesheet" href="styles/zuul.css" />
 </head>
 <body>
-
     <div id="zuul_container"></div>
-
-    <script src="jquery.min.js"></script>
-    <script src="jquery-visibility.js"></script>
-    <script src="jquery.graphite.js"></script>
+    <script src="lib/jquery.min.js"></script>
+    <script src="lib/jquery-visibility.js"></script>
+    <script src="lib/jquery.graphite.js"></script>
     <script src="jquery.zuul.js"></script>
     <script src="zuul.app.js"></script>
     <script>
diff --git a/etc/status/public_html/jquery.zuul.js b/etc/status/public_html/jquery.zuul.js
index c13e48c..40a5d4d 100644
--- a/etc/status/public_html/jquery.zuul.js
+++ b/etc/status/public_html/jquery.zuul.js
@@ -316,9 +316,11 @@
                 var $enqueue_time = $('<small />').addClass('time')
                     .attr('title', 'Elapsed Time').html(enqueue_time);
 
-                var $right = $('<div />')
-                    .addClass('col-xs-4 text-right')
-                    .append($remaining_time, $('<br />'), $enqueue_time);
+                var $right = $('<div />');
+                if (change.live === true) {
+                    $right.addClass('col-xs-4 text-right')
+                        .append($remaining_time, $('<br />'), $enqueue_time);
+                }
 
                 var $header = $('<div />')
                     .addClass('row')
@@ -373,7 +375,7 @@
                 else if (change.live !== true) {
                     // Grey icon
                     icon_name = 'grey.png';
-                    icon_title = 'Dependent change independently tested';
+                    icon_title = 'Dependent change required for testing';
                 }
                 else if (change.failing_reasons &&
                          change.failing_reasons.length > 0) {
@@ -840,7 +842,9 @@
                     });
                     $.each(change_queue.heads, function(head_i, head) {
                         $.each(head, function(change_i, change) {
-                            count += 1;
+                            if (change.live === true) {
+                                count += 1;
+                            }
                             var idx = tree.indexOf(change.id);
                             if (idx > -1) {
                                 change._tree_index = idx;
diff --git a/etc/status/public_html/zuul.app.js b/etc/status/public_html/zuul.app.js
index 6f87a92..640437b 100644
--- a/etc/status/public_html/zuul.app.js
+++ b/etc/status/public_html/zuul.app.js
@@ -39,6 +39,9 @@
     });
 }
 
+/**
+ * @return The $.zuul instance
+ */
 function zuul_start($) {
     // Start the zuul app (expects default dom)
 
@@ -94,4 +97,6 @@
             }
         });
     });
-}
\ No newline at end of file
+
+    return zuul;
+}
diff --git a/requirements.txt b/requirements.txt
index b24d171..c682999 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,14 +5,13 @@
 Paste
 WebOb>=1.2.3,<1.3
 paramiko>=1.8.0
-GitPython>=0.3.2.1
-lockfile>=0.8
+GitPython>=0.3.3
 ordereddict
 python-daemon>=2.0.4
 extras
 statsd>=1.0.0,<3.0
 voluptuous>=0.7
-gear>=0.5.4,<1.0.0
+gear>=0.5.7,<1.0.0
 apscheduler>=2.1.1,<3.0
 PrettyTable>=0.6,<0.8
 babel>=1.0
diff --git a/tests/base.py b/tests/base.py
index 5ae0d3e..8c96d18 100755
--- a/tests/base.py
+++ b/tests/base.py
@@ -378,6 +378,8 @@
 
 
 class FakeGerrit(object):
+    log = logging.getLogger("zuul.test.FakeGerrit")
+
     def __init__(self, *args, **kw):
         self.event_queue = Queue.Queue()
         self.fixture_dir = os.path.join(FIXTURE_DIR, 'gerrit')
@@ -394,7 +396,7 @@
         return c
 
     def addEvent(self, data):
-        return self.event_queue.put(data)
+        return self.event_queue.put((time.time(), data))
 
     def getEvent(self):
         return self.event_queue.get()
@@ -418,12 +420,18 @@
         return {}
 
     def simpleQuery(self, query):
+        self.log.debug("simpleQuery: %s" % query)
         self.queries.append(query)
         if query.startswith('change:'):
             # Query a specific changeid
             changeid = query[len('change:'):]
             l = [change.query() for change in self.changes.values()
                  if change.data['id'] == changeid]
+        elif query.startswith('message:'):
+            # Query the content of a commit message
+            msg = query[len('message:'):].strip()
+            l = [change.query() for change in self.changes.values()
+                 if msg in change.data['commitMessage']]
         else:
             # Query all open changes
             l = [change.query() for change in self.changes.values()]
@@ -471,6 +479,7 @@
     def __init__(self, upstream_root, *args):
         super(FakeGerritTrigger, self).__init__(*args)
         self.upstream_root = upstream_root
+        self.gerrit_connector.delay = 0.0
 
     def getGitUrl(self, project):
         return os.path.join(self.upstream_root, project.name)
@@ -811,11 +820,11 @@
         return endpoint, ''
 
 
-class ZuulTestCase(testtools.TestCase):
+class BaseTestCase(testtools.TestCase):
     log = logging.getLogger("zuul.test")
 
     def setUp(self):
-        super(ZuulTestCase, self).setUp()
+        super(BaseTestCase, self).setUp()
         test_timeout = os.environ.get('OS_TEST_TIMEOUT', 0)
         try:
             test_timeout = int(test_timeout)
@@ -839,6 +848,12 @@
                 level=logging.DEBUG,
                 format='%(asctime)s %(name)-32s '
                 '%(levelname)-8s %(message)s'))
+
+
+class ZuulTestCase(BaseTestCase):
+
+    def setUp(self):
+        super(ZuulTestCase, self).setUp()
         if USE_TEMPDIR:
             tmp_root = self.useFixture(fixtures.TempDir(
                 rootdir=os.environ.get("ZUUL_TEST_ROOT"))
@@ -1101,6 +1116,12 @@
         while len(self.gearman_server.functions) < count:
             time.sleep(0)
 
+    def orderedRelease(self):
+        # Run one build at a time to ensure non-race order:
+        while len(self.builds):
+            self.release(self.builds[0])
+            self.waitUntilSettled()
+
     def release(self, job):
         if isinstance(job, FakeBuild):
             job.release()
@@ -1153,8 +1174,6 @@
         return True
 
     def areAllBuildsWaiting(self):
-        ret = True
-
         builds = self.launcher.builds.values()
         for build in builds:
             client_job = None
@@ -1166,35 +1185,34 @@
             if not client_job:
                 self.log.debug("%s is not known to the gearman client" %
                                build)
-                ret = False
-                continue
+                return False
             if not client_job.handle:
                 self.log.debug("%s has no handle" % client_job)
-                ret = False
-                continue
+                return False
             server_job = self.gearman_server.jobs.get(client_job.handle)
             if not server_job:
                 self.log.debug("%s is not known to the gearman server" %
                                client_job)
-                ret = False
-                continue
+                return False
             if not hasattr(server_job, 'waiting'):
                 self.log.debug("%s is being enqueued" % server_job)
-                ret = False
-                continue
+                return False
             if server_job.waiting:
                 continue
             worker_job = self.worker.gearman_jobs.get(server_job.unique)
             if worker_job:
+                if build.number is None:
+                    self.log.debug("%s has not reported start" % worker_job)
+                    return False
                 if worker_job.build.isWaiting():
                     continue
                 else:
                     self.log.debug("%s is running" % worker_job)
-                    ret = False
+                    return False
             else:
                 self.log.debug("%s is unassigned" % server_job)
-                ret = False
-        return ret
+                return False
+        return True
 
     def waitUntilSettled(self):
         self.log.debug("Waiting until settled...")
diff --git a/tests/fixtures/layout-no-timer.yaml b/tests/fixtures/layout-no-timer.yaml
index 9436821..ca40d13 100644
--- a/tests/fixtures/layout-no-timer.yaml
+++ b/tests/fixtures/layout-no-timer.yaml
@@ -1,14 +1,28 @@
 pipelines:
+  - name: check
+    manager: IndependentPipelineManager
+    trigger:
+      gerrit:
+        - event: patchset-created
+    success:
+      gerrit:
+        verified: 1
+    failure:
+      gerrit:
+        verified: -1
+
   - name: periodic
     manager: IndependentPipelineManager
     # Trigger is required, set it to one that is a noop
     # during tests that check the timer trigger.
     trigger:
       gerrit:
-        - event: patchset-created
+        - event: ref-updated
 
 projects:
   - name: org/project
+    check:
+      - project-test1
     periodic:
       - project-bitrot-stable-old
       - project-bitrot-stable-older
diff --git a/tests/fixtures/layout-skip-if.yaml b/tests/fixtures/layout-skip-if.yaml
new file mode 100644
index 0000000..0cfb445
--- /dev/null
+++ b/tests/fixtures/layout-skip-if.yaml
@@ -0,0 +1,29 @@
+pipelines:
+  - name: check
+    manager: IndependentPipelineManager
+    trigger:
+      gerrit:
+        - event: patchset-created
+    success:
+      gerrit:
+        verified: 1
+    failure:
+      gerrit:
+        verified: -1
+
+
+jobs:
+  # Defining a metajob will validate that the skip-if attribute of the
+  # metajob is correctly copied to the job.
+  - name: ^.*skip-if$
+    skip-if:
+      - project: ^org/project$
+        branch: ^master$
+        all-files-match-any:
+          - ^README$
+  - name: project-test-skip-if
+
+projects:
+  - name: org/project
+    check:
+      - project-test-skip-if
diff --git a/tests/test_change_matcher.py b/tests/test_change_matcher.py
new file mode 100644
index 0000000..1f4ab93
--- /dev/null
+++ b/tests/test_change_matcher.py
@@ -0,0 +1,154 @@
+# Copyright 2015 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from zuul import change_matcher as cm
+from zuul import model
+
+from tests.base import BaseTestCase
+
+
+class BaseTestMatcher(BaseTestCase):
+
+    project = 'project'
+
+    def setUp(self):
+        super(BaseTestMatcher, self).setUp()
+        self.change = model.Change(self.project)
+
+
+class TestAbstractChangeMatcher(BaseTestMatcher):
+
+    def test_str(self):
+        matcher = cm.ProjectMatcher(self.project)
+        self.assertEqual(str(matcher), '{ProjectMatcher:project}')
+
+    def test_repr(self):
+        matcher = cm.ProjectMatcher(self.project)
+        self.assertEqual(repr(matcher), '<ProjectMatcher project>')
+
+
+class TestProjectMatcher(BaseTestMatcher):
+
+    def test_matches_returns_true(self):
+        matcher = cm.ProjectMatcher(self.project)
+        self.assertTrue(matcher.matches(self.change))
+
+    def test_matches_returns_false(self):
+        matcher = cm.ProjectMatcher('not_project')
+        self.assertFalse(matcher.matches(self.change))
+
+
+class TestBranchMatcher(BaseTestMatcher):
+
+    def setUp(self):
+        super(TestBranchMatcher, self).setUp()
+        self.matcher = cm.BranchMatcher('foo')
+
+    def test_matches_returns_true_on_matching_branch(self):
+        self.change.branch = 'foo'
+        self.assertTrue(self.matcher.matches(self.change))
+
+    def test_matches_returns_true_on_matching_ref(self):
+        self.change.branch = 'bar'
+        self.change.ref = 'foo'
+        self.assertTrue(self.matcher.matches(self.change))
+
+    def test_matches_returns_false_for_no_match(self):
+        self.change.branch = 'bar'
+        self.change.ref = 'baz'
+        self.assertFalse(self.matcher.matches(self.change))
+
+    def test_matches_returns_false_for_missing_attrs(self):
+        delattr(self.change, 'branch')
+        # ref is by default not an attribute
+        self.assertFalse(self.matcher.matches(self.change))
+
+
+class TestFileMatcher(BaseTestMatcher):
+
+    def setUp(self):
+        super(TestFileMatcher, self).setUp()
+        self.matcher = cm.FileMatcher('filename')
+
+    def test_matches_returns_true(self):
+        self.change.files = ['filename']
+        self.assertTrue(self.matcher.matches(self.change))
+
+    def test_matches_returns_false_when_no_files(self):
+        self.assertFalse(self.matcher.matches(self.change))
+
+    def test_matches_returns_false_when_files_attr_missing(self):
+        delattr(self.change, 'files')
+        self.assertFalse(self.matcher.matches(self.change))
+
+
+class TestAbstractMatcherCollection(BaseTestMatcher):
+
+    def test_str(self):
+        matcher = cm.MatchAll([cm.FileMatcher('foo')])
+        self.assertEqual(str(matcher), '{MatchAll:{FileMatcher:foo}}')
+
+    def test_repr(self):
+        matcher = cm.MatchAll([])
+        self.assertEqual(repr(matcher), '<MatchAll>')
+
+
+class TestMatchAllFiles(BaseTestMatcher):
+
+    def setUp(self):
+        super(TestMatchAllFiles, self).setUp()
+        self.matcher = cm.MatchAllFiles([cm.FileMatcher('^docs/.*$')])
+
+    def _test_matches(self, expected, files=None):
+        if files is not None:
+            self.change.files = files
+        self.assertEqual(expected, self.matcher.matches(self.change))
+
+    def test_matches_returns_false_when_files_attr_missing(self):
+        delattr(self.change, 'files')
+        self._test_matches(False)
+
+    def test_matches_returns_false_when_no_files(self):
+        self._test_matches(False)
+
+    def test_matches_returns_false_when_not_all_files_match(self):
+        self._test_matches(False, files=['docs/foo', 'foo/bar'])
+
+    def test_matches_returns_true_when_commit_message_matches(self):
+        self._test_matches(True, files=['/COMMIT_MSG'])
+
+    def test_matches_returns_true_when_all_files_match(self):
+        self._test_matches(True, files=['docs/foo'])
+
+
+class TestMatchAll(BaseTestMatcher):
+
+    def test_matches_returns_true(self):
+        matcher = cm.MatchAll([cm.ProjectMatcher(self.project)])
+        self.assertTrue(matcher.matches(self.change))
+
+    def test_matches_returns_false_for_missing_matcher(self):
+        matcher = cm.MatchAll([cm.ProjectMatcher('not_project')])
+        self.assertFalse(matcher.matches(self.change))
+
+
+class TestMatchAny(BaseTestMatcher):
+
+    def test_matches_returns_true(self):
+        matcher = cm.MatchAny([cm.ProjectMatcher(self.project)])
+        self.assertTrue(matcher.matches(self.change))
+
+    def test_matches_returns_false(self):
+        matcher = cm.MatchAny([cm.ProjectMatcher('not_project')])
+        self.assertFalse(matcher.matches(self.change))
diff --git a/tests/test_model.py b/tests/test_model.py
new file mode 100644
index 0000000..2711618
--- /dev/null
+++ b/tests/test_model.py
@@ -0,0 +1,64 @@
+# Copyright 2015 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from zuul import change_matcher as cm
+from zuul import model
+
+from tests.base import BaseTestCase
+
+
+class TestJob(BaseTestCase):
+
+    @property
+    def job(self):
+        job = model.Job('job')
+        job.skip_if_matcher = cm.MatchAll([
+            cm.ProjectMatcher('^project$'),
+            cm.MatchAllFiles([cm.FileMatcher('^docs/.*$')]),
+        ])
+        return job
+
+    def test_change_matches_returns_false_for_matched_skip_if(self):
+        change = model.Change('project')
+        change.files = ['docs/foo']
+        self.assertFalse(self.job.changeMatches(change))
+
+    def test_change_matches_returns_true_for_unmatched_skip_if(self):
+        change = model.Change('project')
+        change.files = ['foo']
+        self.assertTrue(self.job.changeMatches(change))
+
+    def test_copy_retains_skip_if(self):
+        job = model.Job('job')
+        job.copy(self.job)
+        self.assertTrue(job.skip_if_matcher)
+
+    def _assert_job_booleans_are_not_none(self, job):
+        self.assertIsNotNone(job.voting)
+        self.assertIsNotNone(job.hold_following_changes)
+
+    def test_job_sets_defaults_for_boolean_attributes(self):
+        job = model.Job('job')
+        self._assert_job_booleans_are_not_none(job)
+
+    def test_metajob_does_not_set_defaults_for_boolean_attributes(self):
+        job = model.Job('^job')
+        self.assertIsNone(job.voting)
+        self.assertIsNone(job.hold_following_changes)
+
+    def test_metajob_copy_does_not_set_undefined_boolean_attributes(self):
+        job = model.Job('job')
+        metajob = model.Job('^job')
+        job.copy(metajob)
+        self._assert_job_booleans_are_not_none(job)
diff --git a/tests/test_scheduler.py b/tests/test_scheduler.py
index dcf7a8b..3b59e3e 100755
--- a/tests/test_scheduler.py
+++ b/tests/test_scheduler.py
@@ -22,22 +22,62 @@
 import time
 import urllib
 import urllib2
+import yaml
 
 import git
 import testtools
 
+import zuul.change_matcher
 import zuul.scheduler
 import zuul.rpcclient
 import zuul.reporter.gerrit
 import zuul.reporter.smtp
 
-from tests.base import ZuulTestCase, repack_repo
+from tests.base import (
+    BaseTestCase,
+    ZuulTestCase,
+    repack_repo,
+)
 
 logging.basicConfig(level=logging.DEBUG,
                     format='%(asctime)s %(name)-32s '
                     '%(levelname)-8s %(message)s')
 
 
+class TestSchedulerConfigParsing(BaseTestCase):
+
+    def test_parse_skip_if(self):
+        job_yaml = """
+jobs:
+  - name: job_name
+    skip-if:
+      - project: ^project_name$
+        branch: ^stable/icehouse$
+        all-files-match-any:
+          - ^filename$
+      - project: ^project2_name$
+        all-files-match-any:
+          - ^filename2$
+    """.strip()
+        data = yaml.load(job_yaml)
+        config_job = data.get('jobs')[0]
+        sched = zuul.scheduler.Scheduler()
+        cm = zuul.change_matcher
+        expected = cm.MatchAny([
+            cm.MatchAll([
+                cm.ProjectMatcher('^project_name$'),
+                cm.BranchMatcher('^stable/icehouse$'),
+                cm.MatchAllFiles([cm.FileMatcher('^filename$')]),
+            ]),
+            cm.MatchAll([
+                cm.ProjectMatcher('^project2_name$'),
+                cm.MatchAllFiles([cm.FileMatcher('^filename2$')]),
+            ]),
+        ])
+        matcher = sched._parseSkipIf(config_job)
+        self.assertEqual(expected, matcher)
+
+
 class TestScheduler(ZuulTestCase):
 
     def test_jobs_launched(self):
@@ -1670,6 +1710,41 @@
         self.assertEqual(A.reported, 0, "Abandoned change should not report")
         self.assertEqual(B.reported, 1, "Change should report")
 
+    def test_abandoned_not_timer(self):
+        "Test that an abandoned change does not cancel timer jobs"
+
+        self.worker.hold_jobs_in_build = True
+
+        # Start timer trigger - also org/project
+        self.config.set('zuul', 'layout_config',
+                        'tests/fixtures/layout-idle.yaml')
+        self.sched.reconfigure(self.config)
+        self.registerJobs()
+        # The pipeline triggers every second, so we should have seen
+        # several by now.
+        time.sleep(5)
+        self.waitUntilSettled()
+        # Stop queuing timer triggered jobs so that the assertions
+        # below don't race against more jobs being queued.
+        self.config.set('zuul', 'layout_config',
+                        'tests/fixtures/layout-no-timer.yaml')
+        self.sched.reconfigure(self.config)
+        self.registerJobs()
+        self.assertEqual(len(self.builds), 2, "Two timer jobs")
+
+        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(len(self.builds), 3, "One change plus two timer jobs")
+
+        self.fake_gerrit.addEvent(A.getChangeAbandonedEvent())
+        self.waitUntilSettled()
+
+        self.assertEqual(len(self.builds), 2, "Two timer jobs remain")
+
+        self.worker.release()
+        self.waitUntilSettled()
+
     def test_zuul_url_return(self):
         "Test if ZUUL_URL is returning when zuul_url is set in zuul.conf"
         self.assertTrue(self.sched.config.has_option('merger', 'zuul_url'))
@@ -1965,6 +2040,33 @@
         self.assertEqual(B.data['status'], 'MERGED')
         self.assertEqual(B.reported, 2)
 
+    def _test_skip_if_jobs(self, branch, should_skip):
+        "Test that jobs with a skip-if filter run only when appropriate"
+        self.config.set('zuul', 'layout_config',
+                        'tests/fixtures/layout-skip-if.yaml')
+        self.sched.reconfigure(self.config)
+        self.registerJobs()
+
+        change = self.fake_gerrit.addFakeChange('org/project',
+                                                branch,
+                                                'test skip-if')
+        self.fake_gerrit.addEvent(change.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        tested_change_ids = [x.changes[0] for x in self.history
+                             if x.name == 'project-test-skip-if']
+
+        if should_skip:
+            self.assertEqual([], tested_change_ids)
+        else:
+            self.assertIn(change.data['number'], tested_change_ids)
+
+    def test_skip_if_match_skips_job(self):
+        self._test_skip_if_jobs(branch='master', should_skip=True)
+
+    def test_skip_if_no_match_runs_job(self):
+        self._test_skip_if_jobs(branch='mp', should_skip=False)
+
     def test_test_config(self):
         "Test that we can test the config"
         sched = zuul.scheduler.Scheduler()
@@ -2022,9 +2124,7 @@
         self.waitUntilSettled()
 
         # Run one build at a time to ensure non-race order:
-        for x in range(6):
-            self.release(self.builds[0])
-            self.waitUntilSettled()
+        self.orderedRelease()
         self.worker.hold_jobs_in_build = False
         self.waitUntilSettled()
 
@@ -2053,7 +2153,10 @@
         self.assertIn('Content-Type', headers)
         self.assertEqual(headers['Content-Type'],
                          'application/json; charset=UTF-8')
+        self.assertIn('Access-Control-Allow-Origin', headers)
+        self.assertIn('Cache-Control', headers)
         self.assertIn('Last-Modified', headers)
+        self.assertIn('Expires', headers)
         data = f.read()
 
         self.worker.hold_jobs_in_build = False
@@ -3005,7 +3108,6 @@
                 self.assertEqual('project-merge', job['name'])
                 self.assertEqual('gate', job['pipeline'])
                 self.assertEqual(False, job['retry'])
-                self.assertEqual(13, len(job['parameters']))
                 self.assertEqual('https://server/job/project-merge/0/',
                                  job['url'])
                 self.assertEqual(7, len(job['worker']))
@@ -3216,6 +3318,45 @@
         self.assertEqual(A.data['status'], 'MERGED')
         self.assertEqual(A.reported, 2)
 
+    def test_crd_gate_reverse(self):
+        "Test reverse cross-repo dependencies"
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project2', 'master', 'B')
+        A.addApproval('CRVW', 2)
+        B.addApproval('CRVW', 2)
+
+        # A Depends-On: B
+
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['id'])
+
+        self.fake_gerrit.addEvent(A.addApproval('APRV', 1))
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(B.data['status'], 'NEW')
+
+        self.worker.hold_jobs_in_build = True
+        A.addApproval('APRV', 1)
+        self.fake_gerrit.addEvent(B.addApproval('APRV', 1))
+        self.waitUntilSettled()
+
+        self.worker.release('.*-merge')
+        self.waitUntilSettled()
+        self.worker.release('.*-merge')
+        self.waitUntilSettled()
+        self.worker.hold_jobs_in_build = False
+        self.worker.release()
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'MERGED')
+        self.assertEqual(B.data['status'], 'MERGED')
+        self.assertEqual(A.reported, 2)
+        self.assertEqual(B.reported, 2)
+
+        self.assertEqual(self.getJobFromHistory('project1-merge').changes,
+                         '2,1 1,1')
+
     def test_crd_cycle(self):
         "Test cross-repo dependency cycles"
         A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
@@ -3282,7 +3423,7 @@
 
     def test_crd_check_git_depends(self):
         "Test single-repo dependencies in independent pipelines"
-        self.gearman_server.hold_jobs_in_queue = True
+        self.gearman_server.hold_jobs_in_build = True
         A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
         B = self.fake_gerrit.addFakeChange('org/project1', 'master', 'B')
 
@@ -3294,8 +3435,8 @@
         self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
         self.waitUntilSettled()
 
-        self.gearman_server.hold_jobs_in_queue = False
-        self.gearman_server.release()
+        self.orderedRelease()
+        self.gearman_server.hold_jobs_in_build = False
         self.waitUntilSettled()
 
         self.assertEqual(A.data['status'], 'NEW')
@@ -3312,7 +3453,7 @@
 
     def test_crd_check_duplicate(self):
         "Test duplicate check in independent pipelines"
-        self.gearman_server.hold_jobs_in_queue = True
+        self.worker.hold_jobs_in_build = True
         A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
         B = self.fake_gerrit.addFakeChange('org/project1', 'master', 'B')
         check_pipeline = self.sched.layout.pipelines['check']
@@ -3333,12 +3474,11 @@
         self.waitUntilSettled()
         self.assertEqual(len(check_pipeline.getAllItems()), 3)
 
-        self.gearman_server.hold_jobs_in_queue = False
-        self.gearman_server.release('.*-merge')
-        self.waitUntilSettled()
-        self.gearman_server.release('.*-merge')
-        self.waitUntilSettled()
-        self.gearman_server.release()
+        # Release jobs in order to avoid races with change A jobs
+        # finishing before change B jobs.
+        self.orderedRelease()
+        self.worker.hold_jobs_in_build = False
+        self.worker.release()
         self.waitUntilSettled()
 
         self.assertEqual(A.data['status'], 'NEW')
@@ -3435,3 +3575,43 @@
         # Each job should have tested exactly one change
         for job in self.history:
             self.assertEqual(len(job.changes.split()), 1)
+
+    def test_crd_check_transitive(self):
+        "Test transitive cross-repo dependencies"
+        # Specifically, if A -> B -> C, and C gets a new patchset and
+        # A gets a new patchset, ensure the test of A,2 includes B,1
+        # and C,2 (not C,1 which would indicate stale data in the
+        # cache for B).
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A')
+        B = self.fake_gerrit.addFakeChange('org/project2', 'master', 'B')
+        C = self.fake_gerrit.addFakeChange('org/project3', 'master', 'C')
+
+        # A Depends-On: B
+        A.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            A.subject, B.data['id'])
+
+        # B Depends-On: C
+        B.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            B.subject, C.data['id'])
+
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(self.history[-1].changes, '3,1 2,1 1,1')
+
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(self.history[-1].changes, '3,1 2,1')
+
+        self.fake_gerrit.addEvent(C.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+        self.assertEqual(self.history[-1].changes, '3,1')
+
+        C.addPatchset()
+        self.fake_gerrit.addEvent(C.getPatchsetCreatedEvent(2))
+        self.waitUntilSettled()
+        self.assertEqual(self.history[-1].changes, '3,2')
+
+        A.addPatchset()
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(2))
+        self.waitUntilSettled()
+        self.assertEqual(self.history[-1].changes, '3,2 2,1 1,2')
diff --git a/tests/test_zuultrigger.py b/tests/test_zuultrigger.py
index a26fa86..2f0e4f0 100644
--- a/tests/test_zuultrigger.py
+++ b/tests/test_zuultrigger.py
@@ -111,8 +111,8 @@
             "merged with the current state of the repository. Please rebase "
             "your change and upload a new patchset.")
 
-        self.assertEqual(self.fake_gerrit.queries[0],
-                         "project:org/project status:open")
+        self.assertTrue("project:org/project status:open" in
+                        self.fake_gerrit.queries)
 
         # Reconfigure and run the test again.  This is a regression
         # check to make sure that we don't end up with a stale trigger
diff --git a/tools/zuul-changes.py b/tools/zuul-changes.py
index 7fc541b..9dbf504 100755
--- a/tools/zuul-changes.py
+++ b/tools/zuul-changes.py
@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 # Copyright 2013 OpenStack Foundation
+# Copyright 2015 Hewlett-Packard Development Company, L.P.
 #
 # Licensed under the Apache License, Version 2.0 (the "License"); you may
 # not use this file except in compliance with the License. You may obtain
@@ -13,9 +14,6 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-# Print commands to leave gerrit comments for every change in one of
-# Zuul's pipelines.
-
 import urllib2
 import json
 import argparse
@@ -23,9 +21,6 @@
 parser = argparse.ArgumentParser()
 parser.add_argument('url', help='The URL of the running Zuul instance')
 parser.add_argument('pipeline_name', help='The name of the Zuul pipeline')
-parser.add_argument('comment', help='The text of the Gerrit comment')
-parser.add_argument('--review-host', default='review',
-                    help='The Gerrit hostname')
 options = parser.parse_args()
 
 data = urllib2.urlopen('%s/status.json' % options.url).read()
@@ -37,7 +32,13 @@
     for queue in pipeline['change_queues']:
         for head in queue['heads']:
             for change in head:
-                print 'ssh %s gerrit review %s --message \\"%s\\"' % (
-                    options.review_host,
-                    change['id'],
-                    options.comment)
+                if not change['live']:
+                    continue
+                cid, cps = change['id'].split(',')
+                print (
+                    "zuul enqueue --trigger gerrit --pipeline %s "
+                    "--project %s --change %s,%s" % (
+                        options.pipeline_name,
+                        change['project'],
+                        cid, cps)
+                )
diff --git a/zuul/change_matcher.py b/zuul/change_matcher.py
new file mode 100644
index 0000000..ed380f0
--- /dev/null
+++ b/zuul/change_matcher.py
@@ -0,0 +1,132 @@
+# Copyright 2015 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+"""
+This module defines classes used in matching changes based on job
+configuration.
+"""
+
+import re
+
+
+class AbstractChangeMatcher(object):
+
+    def __init__(self, regex):
+        self._regex = regex
+        self.regex = re.compile(regex)
+
+    def matches(self, change):
+        """Return a boolean indication of whether change matches
+        implementation-specific criteria.
+        """
+        raise NotImplementedError()
+
+    def copy(self):
+        return self.__class__(self._regex)
+
+    def __eq__(self, other):
+        return str(self) == str(other)
+
+    def __str__(self):
+        return '{%s:%s}' % (self.__class__.__name__, self._regex)
+
+    def __repr__(self):
+        return '<%s %s>' % (self.__class__.__name__, self._regex)
+
+
+class ProjectMatcher(AbstractChangeMatcher):
+
+    def matches(self, change):
+        return self.regex.match(str(change.project))
+
+
+class BranchMatcher(AbstractChangeMatcher):
+
+    def matches(self, change):
+        return (
+            (hasattr(change, 'branch') and self.regex.match(change.branch)) or
+            (hasattr(change, 'ref') and self.regex.match(change.ref))
+        )
+
+
+class FileMatcher(AbstractChangeMatcher):
+
+    def matches(self, change):
+        if not hasattr(change, 'files'):
+            return False
+        for file_ in change.files:
+            if self.regex.match(file_):
+                return True
+        return False
+
+
+class AbstractMatcherCollection(AbstractChangeMatcher):
+
+    def __init__(self, matchers):
+        self.matchers = matchers
+
+    def __eq__(self, other):
+        return str(self) == str(other)
+
+    def __str__(self):
+        return '{%s:%s}' % (self.__class__.__name__,
+                            ','.join([str(x) for x in self.matchers]))
+
+    def __repr__(self):
+        return '<%s>' % self.__class__.__name__
+
+    def copy(self):
+        return self.__class__(self.matchers[:])
+
+
+class MatchAllFiles(AbstractMatcherCollection):
+
+    commit_regex = re.compile('^/COMMIT_MSG$')
+
+    @property
+    def regexes(self):
+        for matcher in self.matchers:
+            yield matcher.regex
+        yield self.commit_regex
+
+    def matches(self, change):
+        if not (hasattr(change, 'files') and change.files):
+            return False
+        for file_ in change.files:
+            matched_file = False
+            for regex in self.regexes:
+                if regex.match(file_):
+                    matched_file = True
+                    break
+            if not matched_file:
+                return False
+        return True
+
+
+class MatchAll(AbstractMatcherCollection):
+
+    def matches(self, change):
+        for matcher in self.matchers:
+            if not matcher.matches(change):
+                return False
+        return True
+
+
+class MatchAny(AbstractMatcherCollection):
+
+    def matches(self, change):
+        for matcher in self.matchers:
+            if matcher.matches(change):
+                return True
+        return False
diff --git a/zuul/cmd/client.py b/zuul/cmd/client.py
index 766a4ef..bc2c152 100644
--- a/zuul/cmd/client.py
+++ b/zuul/cmd/client.py
@@ -232,9 +232,6 @@
             'number': {
                 'title': 'Number'
             },
-            'parameters': {
-                'title': 'Parameters'
-            },
             'worker.name': {
                 'title': 'Worker'
             },
diff --git a/zuul/launcher/gearman.py b/zuul/launcher/gearman.py
index 564a554..653678a 100644
--- a/zuul/launcher/gearman.py
+++ b/zuul/launcher/gearman.py
@@ -231,6 +231,8 @@
                 s_config = {}
                 s_config.update((k, v.format(item=item, job=job,
                                              change=item.change))
+                                if isinstance(v, basestring)
+                                else (k, v)
                                 for k, v in s.items())
 
                 (swift_instructions['URL'],
@@ -402,14 +404,15 @@
             self.log.debug("Removed build %s from queue" % build)
             return
 
+        time.sleep(1)
+
         self.log.debug("Still unable to find build %s to cancel" % build)
         if build.number:
             self.log.debug("Build %s has just started" % build)
-        else:
-            self.log.error("Build %s has not started but was not"
-                           "found in queue; canceling anyway" % build)
-        self.cancelRunningBuild(build)
-        self.log.debug("Canceled possibly running build %s" % build)
+            self.log.debug("Canceled running build %s" % build)
+            self.cancelRunningBuild(build)
+            return
+        self.log.debug("Unable to cancel build %s" % build)
 
     def onBuildCompleted(self, job, result=None):
         if job.unique in self.meta_jobs:
diff --git a/zuul/layoutvalidator.py b/zuul/layoutvalidator.py
index cc7080c..88d10e2 100644
--- a/zuul/layoutvalidator.py
+++ b/zuul/layoutvalidator.py
@@ -135,6 +135,11 @@
              'logserver-prefix': str,
              }
 
+    skip_if = {'project': str,
+               'branch': str,
+               'all-files-match-any': toList(str),
+               }
+
     job = {v.Required('name'): str,
            'queue-name': str,
            'failure-message': str,
@@ -147,6 +152,7 @@
            'branch': toList(str),
            'files': toList(str),
            'swift': toList(swift),
+           'skip-if': toList(skip_if),
            }
     jobs = [job]
 
diff --git a/zuul/lib/cloner.py b/zuul/lib/cloner.py
index 2b35e41..67e238a 100644
--- a/zuul/lib/cloner.py
+++ b/zuul/lib/cloner.py
@@ -125,7 +125,7 @@
 
         repo = self.cloneUpstream(project, dest)
 
-        repo.update()
+        repo.reset()
         # Ensure that we don't have stale remotes around
         repo.prune()
 
diff --git a/zuul/lib/gerrit.py b/zuul/lib/gerrit.py
index 9aeff3d..6c7906b 100644
--- a/zuul/lib/gerrit.py
+++ b/zuul/lib/gerrit.py
@@ -39,7 +39,7 @@
         data = json.loads(l)
         self.log.debug("Received data from Gerrit event stream: \n%s" %
                        pprint.pformat(data))
-        self.gerrit.addEvent(data)
+        self.gerrit.addEvent((time.time(), data))
 
     def _listen(self, stdout, stderr):
         poll = select.poll()
diff --git a/zuul/lib/swift.py b/zuul/lib/swift.py
index 9b9bea3..3c411d3 100644
--- a/zuul/lib/swift.py
+++ b/zuul/lib/swift.py
@@ -147,8 +147,10 @@
                 settings[key] = kwargs[altkey]
             elif self.config.has_option('swift', 'default_' + key):
                 settings[key] = self.config.get('swift', 'default_' + key)
+            # TODO: these are always strings; some should be converted
+            # to ints.
 
-        expires = int(time() + settings['expiry'])
+        expires = int(time() + int(settings['expiry']))
         redirect = ''
 
         url = os.path.join(self.storage_url, settings['container'],
diff --git a/zuul/merger/client.py b/zuul/merger/client.py
index 8d8f7ee..950c385 100644
--- a/zuul/merger/client.py
+++ b/zuul/merger/client.py
@@ -84,10 +84,10 @@
     def submitJob(self, name, data, build_set,
                   precedence=zuul.model.PRECEDENCE_NORMAL):
         uuid = str(uuid4().hex)
-        self.log.debug("Submitting job %s with data %s" % (name, data))
         job = gear.Job(name,
                        json.dumps(data),
                        unique=uuid)
+        self.log.debug("Submitting job %s with data %s" % (job, data))
         self.build_sets[uuid] = build_set
         self.gearman.submitJob(job, precedence=precedence,
                                timeout=300)
diff --git a/zuul/merger/server.py b/zuul/merger/server.py
index 0d105f6..1a02322 100644
--- a/zuul/merger/server.py
+++ b/zuul/merger/server.py
@@ -90,10 +90,10 @@
                 job = self.worker.getJob()
                 try:
                     if job.name == 'merger:merge':
-                        self.log.debug("Got merge job.")
+                        self.log.debug("Got merge job: %s" % job.unique)
                         self.merge(job)
                     elif job.name == 'merger:update':
-                        self.log.debug("Got update job.")
+                        self.log.debug("Got update job: %s" % job.unique)
                         self.update(job)
                     else:
                         self.log.error("Unable to handle job %s" % job.name)
diff --git a/zuul/model.py b/zuul/model.py
index 4514e7d..4d402ff 100644
--- a/zuul/model.py
+++ b/zuul/model.py
@@ -452,12 +452,19 @@
         self.failure_pattern = None
         self.success_pattern = None
         self.parameter_function = None
-        self.hold_following_changes = False
-        self.voting = True
+        # A metajob should only supply values for attributes that have
+        # been explicitly provided, so avoid setting boolean defaults.
+        if self.is_metajob:
+            self.hold_following_changes = None
+            self.voting = None
+        else:
+            self.hold_following_changes = False
+            self.voting = True
         self.branches = []
         self._branches = []
         self.files = []
         self._files = []
+        self.skip_if_matcher = None
         self.swift = {}
 
     def __str__(self):
@@ -466,6 +473,10 @@
     def __repr__(self):
         return '<Job %s>' % (self.name)
 
+    @property
+    def is_metajob(self):
+        return self.name.startswith('^')
+
     def copy(self, other):
         if other.failure_message:
             self.failure_message = other.failure_message
@@ -483,10 +494,15 @@
         if other.files:
             self.files = other.files[:]
             self._files = other._files[:]
+        if other.skip_if_matcher:
+            self.skip_if_matcher = other.skip_if_matcher.copy()
         if other.swift:
             self.swift.update(other.swift)
-        self.hold_following_changes = other.hold_following_changes
-        self.voting = other.voting
+        # Only non-None values should be copied for boolean attributes.
+        if other.hold_following_changes is not None:
+            self.hold_following_changes = other.hold_following_changes
+        if other.voting is not None:
+            self.voting = other.voting
 
     def changeMatches(self, change):
         matches_branch = False
@@ -507,6 +523,9 @@
         if self.files and not matches_file:
             return False
 
+        if self.skip_if_matcher and self.skip_if_matcher.matches(change):
+            return False
+
         return True
 
 
@@ -774,7 +793,6 @@
                 'canceled': build.canceled if build else None,
                 'retry': build.retry if build else None,
                 'number': build.number if build else None,
-                'parameters': build.parameters if build else None,
                 'worker': worker
             })
 
@@ -947,7 +965,8 @@
         return None
 
     def equals(self, other):
-        if (self.project == other.project):
+        if (self.project == other.project
+            and other._id() is None):
             return True
         return False
 
@@ -1263,8 +1282,7 @@
         if name in self.jobs:
             return self.jobs[name]
         job = Job(name)
-        if name.startswith('^'):
-            # This is a meta-job
+        if job.is_metajob:
             regex = re.compile(name)
             self.metajobs.append((regex, job))
         else:
diff --git a/zuul/scheduler.py b/zuul/scheduler.py
index 08a9147..131ad62 100644
--- a/zuul/scheduler.py
+++ b/zuul/scheduler.py
@@ -31,6 +31,7 @@
 import model
 from model import ActionReporter, Pipeline, Project, ChangeQueue
 from model import EventFilter, ChangeishFilter
+from zuul import change_matcher
 from zuul import version as zuul_version
 
 statsd = extras.try_import('statsd.statsd')
@@ -166,6 +167,14 @@
         self.commit = commit
 
 
+def toList(item):
+    if not item:
+        return []
+    if isinstance(item, list):
+        return item
+    return [item]
+
+
 class Scheduler(threading.Thread):
     log = logging.getLogger("zuul.Scheduler")
 
@@ -199,17 +208,38 @@
     def testConfig(self, config_path):
         return self._parseConfig(config_path)
 
+    def _parseSkipIf(self, config_job):
+        cm = change_matcher
+        skip_matchers = []
+
+        for config_skip in config_job.get('skip-if', []):
+            nested_matchers = []
+
+            project_regex = config_skip.get('project')
+            if project_regex:
+                nested_matchers.append(cm.ProjectMatcher(project_regex))
+
+            branch_regex = config_skip.get('branch')
+            if branch_regex:
+                nested_matchers.append(cm.BranchMatcher(branch_regex))
+
+            file_regexes = toList(config_skip.get('all-files-match-any'))
+            if file_regexes:
+                file_matchers = [cm.FileMatcher(x) for x in file_regexes]
+                all_files_matcher = cm.MatchAllFiles(file_matchers)
+                nested_matchers.append(all_files_matcher)
+
+            # All patterns need to match a given skip-if predicate
+            skip_matchers.append(cm.MatchAll(nested_matchers))
+
+        if skip_matchers:
+            # Any skip-if predicate can be matched to trigger a skip
+            return cm.MatchAny(skip_matchers)
+
     def _parseConfig(self, config_path):
         layout = model.Layout()
         project_templates = {}
 
-        def toList(item):
-            if not item:
-                return []
-            if isinstance(item, list):
-                return item
-            return [item]
-
         if config_path:
             config_path = os.path.expanduser(config_path)
             if not os.path.exists(config_path):
@@ -397,6 +427,9 @@
             if files:
                 job._files = files
                 job.files = [re.compile(x) for x in files]
+            skip_if_matcher = self._parseSkipIf(config_job)
+            if skip_if_matcher:
+                job.skip_if_matcher = skip_if_matcher
             swift = toList(config_job.get('swift'))
             if swift:
                 for s in swift:
@@ -979,6 +1012,8 @@
                     efilters += str(b)
                 for f in tree.job._files:
                     efilters += str(f)
+                if tree.job.skip_if_matcher:
+                    efilters += str(tree.job.skip_if_matcher)
                 if efilters:
                     efilters = ' ' + efilters
                 hold = ''
@@ -1330,10 +1365,11 @@
             self.cancelJobs(item)
             self.dequeueItem(item)
             self.pipeline.setDequeuedNeedingChange(item)
-            try:
-                self.reportItem(item)
-            except MergeFailure:
-                pass
+            if item.live:
+                try:
+                    self.reportItem(item)
+                except MergeFailure:
+                    pass
             return (True, nnfi, ready_ahead)
         dep_items = self.getFailingDependentItems(item)
         actionable = change_queue.isActionable(item)
diff --git a/zuul/trigger/gerrit.py b/zuul/trigger/gerrit.py
index c5fdf9a..c28401c 100644
--- a/zuul/trigger/gerrit.py
+++ b/zuul/trigger/gerrit.py
@@ -26,6 +26,7 @@
     """Move events from Gerrit to the scheduler."""
 
     log = logging.getLogger("zuul.GerritEventConnector")
+    delay = 5.0
 
     def __init__(self, gerrit, sched, trigger):
         super(GerritEventConnector, self).__init__()
@@ -37,12 +38,20 @@
 
     def stop(self):
         self._stopped = True
-        self.gerrit.addEvent(None)
+        self.gerrit.addEvent((None, None))
 
     def _handleEvent(self):
-        data = self.gerrit.getEvent()
+        ts, data = self.gerrit.getEvent()
         if self._stopped:
             return
+        # Gerrit can produce inconsistent data immediately after an
+        # event, So ensure that we do not deliver the event to Zuul
+        # until at least a certain amount of time has passed.  Note
+        # that if we receive several events in succession, we will
+        # only need to delay for the first event.  In essence, Zuul
+        # should always be a constant number of seconds behind Gerrit.
+        now = time.time()
+        time.sleep(max((ts + self.delay) - now, 0.0))
         event = TriggerEvent()
         event.type = data.get('type')
         event.trigger_name = self.trigger.name
@@ -362,6 +371,27 @@
             records.extend(self.gerrit.simpleQuery(query))
         return records
 
+    def _getNeededByFromCommit(self, change_id):
+        records = []
+        seen = set()
+        query = 'message:%s' % change_id
+        self.log.debug("Running query %s to find changes needed-by" %
+                       (query,))
+        results = self.gerrit.simpleQuery(query)
+        for result in results:
+            for match in self.depends_on_re.findall(
+                result['commitMessage']):
+                if match != change_id:
+                    continue
+                key = (result['number'], result['currentPatchSet']['number'])
+                if key in seen:
+                    continue
+                self.log.debug("Found change %s,%s needs %s from commit" %
+                               (key[0], key[1], change_id))
+                seen.add(key)
+                records.append(result)
+        return records
+
     def updateChange(self, change, history=None):
         self.log.info("Updating information for %s,%s" %
                       (change.number, change.patchset))
@@ -378,18 +408,19 @@
         change.branch = data['branch']
         change.url = data['url']
         max_ps = 0
-        change.files = []
+        files = []
         for ps in data['patchSets']:
             if ps['number'] == change.patchset:
                 change.refspec = ps['ref']
                 for f in ps.get('files', []):
-                    change.files.append(f['file'])
+                    files.append(f['file'])
             if int(ps['number']) > int(max_ps):
                 max_ps = ps['number']
         if max_ps == change.patchset:
             change.is_current_patchset = True
         else:
             change.is_current_patchset = False
+        change.files = files
 
         change.is_merged = self._isMerged(change)
         change.approvals = data['currentPatchSet'].get('approvals', [])
@@ -408,7 +439,7 @@
             history = history[:]
         history.append(change.number)
 
-        change.needs_changes = []
+        needs_changes = []
         if 'dependsOn' in data:
             parts = data['dependsOn'][0]['ref'].split('/')
             dep_num, dep_ps = parts[3], parts[4]
@@ -418,8 +449,8 @@
             self.log.debug("Getting git-dependent change %s,%s" %
                            (dep_num, dep_ps))
             dep = self._getChange(dep_num, dep_ps, history=history)
-            if (not dep.is_merged) and dep not in change.needs_changes:
-                change.needs_changes.append(dep)
+            if (not dep.is_merged) and dep not in needs_changes:
+                needs_changes.append(dep)
 
         for record in self._getDependsOnFromCommit(data['commitMessage']):
             dep_num = record['number']
@@ -430,17 +461,32 @@
             self.log.debug("Getting commit-dependent change %s,%s" %
                            (dep_num, dep_ps))
             dep = self._getChange(dep_num, dep_ps, history=history)
-            if (not dep.is_merged) and dep not in change.needs_changes:
-                change.needs_changes.append(dep)
+            if (not dep.is_merged) and dep not in needs_changes:
+                needs_changes.append(dep)
+        change.needs_changes = needs_changes
 
-        change.needed_by_changes = []
+        needed_by_changes = []
         if 'neededBy' in data:
             for needed in data['neededBy']:
                 parts = needed['ref'].split('/')
                 dep_num, dep_ps = parts[3], parts[4]
                 dep = self._getChange(dep_num, dep_ps)
                 if (not dep.is_merged) and dep.is_current_patchset:
-                    change.needed_by_changes.append(dep)
+                    needed_by_changes.append(dep)
+
+        for record in self._getNeededByFromCommit(data['id']):
+            dep_num = record['number']
+            dep_ps = record['currentPatchSet']['number']
+            self.log.debug("Getting commit-needed change %s,%s" %
+                           (dep_num, dep_ps))
+            # Because a commit needed-by may be a cross-repo
+            # dependency, cause that change to refresh so that it will
+            # reference the latest patchset of its Depends-On (this
+            # change).
+            dep = self._getChange(dep_num, dep_ps, refresh=True)
+            if (not dep.is_merged) and dep.is_current_patchset:
+                needed_by_changes.append(dep)
+        change.needed_by_changes = needed_by_changes
 
         return change
 
diff --git a/zuul/webapp.py b/zuul/webapp.py
index e289398..44c333b 100644
--- a/zuul/webapp.py
+++ b/zuul/webapp.py
@@ -121,5 +121,10 @@
                 raise webob.exc.HTTPNotFound()
 
         response.headers['Access-Control-Allow-Origin'] = '*'
+
+        response.cache_control.public = True
+        response.cache_control.max_age = self.cache_expiry
         response.last_modified = self.cache_time
-        return response
+        response.expires = self.cache_time + self.cache_expiry
+
+        return response.conditional_response_app