diff --git a/tests/base.py b/tests/base.py
index 65dfe3d..1757a7e 100755
--- a/tests/base.py
+++ b/tests/base.py
@@ -1789,8 +1789,6 @@
         old_urlopen = urllib.request.urlopen
         urllib.request.urlopen = URLOpenerFactory
 
-        self._startMerger()
-
         self.executor_server = RecordingExecutorServer(
             self.config, self.connections,
             jobdir_root=self.test_root,
@@ -2066,8 +2064,6 @@
     def shutdown(self):
         self.log.debug("Shutting down after tests")
         self.executor_client.stop()
-        self.merge_server.stop()
-        self.merge_server.join()
         self.merge_client.stop()
         self.executor_server.stop()
         self.sched.stop()
diff --git a/tests/unit/test_scheduler.py b/tests/unit/test_scheduler.py
index f394c0c..d416369 100755
--- a/tests/unit/test_scheduler.py
+++ b/tests/unit/test_scheduler.py
@@ -1012,6 +1012,7 @@
         self.fake_gerrit.addEvent(A.addApproval('approved', 1))
         self.waitUntilSettled()
         self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
         self.fake_gerrit.addEvent(C.getPatchsetCreatedEvent(1))
         self.waitUntilSettled()
 
@@ -1509,8 +1510,8 @@
         tenant = self.sched.abide.tenants.get('tenant-one')
         trusted, project = tenant.getProject('org/project')
         url = self.fake_gerrit.getGitUrl(project)
-        self.merge_server.merger._addProject('review.example.com',
-                                             'org/project', url)
+        self.executor_server.merger._addProject('review.example.com',
+                                                'org/project', url)
         A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
         A.addPatchset(large=True)
         # TODOv3(jeblair): add hostname to upstream root
diff --git a/zuul/manager/__init__.py b/zuul/manager/__init__.py
index 5b32e5b..d13a1b4 100644
--- a/zuul/manager/__init__.py
+++ b/zuul/manager/__init__.py
@@ -522,6 +522,10 @@
             build_set.setConfiguration()
         if build_set.merge_state == build_set.NEW:
             return self.scheduleMerge(item, ['zuul.yaml', '.zuul.yaml'])
+        if build_set.merge_state == build_set.PENDING:
+            return False
+        if build_set.unable_to_merge:
+            return False
         if build_set.config_error:
             return False
         return True