diff --git a/tests/base.py b/tests/base.py
index 08b3cab..becc854 100755
--- a/tests/base.py
+++ b/tests/base.py
@@ -396,7 +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()
@@ -479,6 +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)
@@ -1167,8 +1168,6 @@
         return True
 
     def areAllBuildsWaiting(self):
-        ret = True
-
         builds = self.launcher.builds.values()
         for build in builds:
             client_job = None
@@ -1180,35 +1179,34 @@
             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/test_scheduler.py b/tests/test_scheduler.py
index 8e0a54b..0779bfa 100755
--- a/tests/test_scheduler.py
+++ b/tests/test_scheduler.py
@@ -3438,10 +3438,13 @@
         self.waitUntilSettled()
         self.assertEqual(len(check_pipeline.getAllItems()), 3)
 
-        self.gearman_server.hold_jobs_in_queue = False
+        # Release jobs in order to avoid races with change A jobs
+        # finishing before change B jobs.
         self.gearman_server.release('.*-merge')
+        self.gearman_server.release('project1-.*')
         self.waitUntilSettled()
         self.gearman_server.release('.*-merge')
+        self.gearman_server.release('project1-.*')
         self.waitUntilSettled()
         self.gearman_server.release()
         self.waitUntilSettled()
diff --git a/zuul/launcher/gearman.py b/zuul/launcher/gearman.py
index 915151e..653678a 100644
--- a/zuul/launcher/gearman.py
+++ b/zuul/launcher/gearman.py
@@ -404,14 +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/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/trigger/gerrit.py b/zuul/trigger/gerrit.py
index 7d970ad..a99db4d 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