Fix wrong matched project template

When having the two branches stable and stable-foo with distinct
project pipelines that pull in different project-templates currently
both project-templates match. The project-templates in this case get
implicit branch matchers. However the implied branch matcher currently
only does a partial match and so a change to stable-foo matches the
project-templates of both stable and stable-foo.

Fix this by changing the implied branch matchers to do full matching.

Change-Id: I569db50f05c1b53cb1fb26e84ea0af377e3df73c

tests/unit/test_scheduler.py

@@ -5451,6 +5451,36 @@ class TestSchedulerTemplatedProject(ZuulTestCase):
             self.getJobFromHistory('project-test1').
             parameters['zuul']['_inheritance_path'])
 
+        # Now create a new branch named stable-foo and change the project
+        # pipeline
+        self.create_branch('untrusted-config', 'stable-foo')
+        self.fake_gerrit.addEvent(
+            self.fake_gerrit.getFakeBranchCreatedEvent(
+                'untrusted-config', 'stable-foo'))
+        self.waitUntilSettled()
+
+        in_repo_conf = textwrap.dedent(
+            """
+            - project:
+                name: untrusted-config
+                templates:
+                  - test-three-and-four
+            """)
+        file_dict = {'zuul.d/project.yaml': in_repo_conf}
+        B = self.fake_gerrit.addFakeChange('untrusted-config', 'stable-foo',
+                                           'B', files=file_dict)
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        self.assertHistory([
+            dict(name='project-test1', result='SUCCESS', changes='1,1'),
+            dict(name='project-test2', result='SUCCESS', changes='1,1'),
+            dict(name='layered-project-test3', result='SUCCESS',
+                 changes='2,1'),
+            dict(name='layered-project-test4', result='SUCCESS',
+                 changes='2,1'),
+        ], ordered=False)
+
 
 class TestSchedulerSuccessURL(ZuulTestCase):
     tenant_config_file = 'config/success-url/main.yaml'

zuul/change_matcher.py

@@ -77,7 +77,7 @@ class ImpliedBranchMatcher(AbstractChangeMatcher):
 
     def matches(self, change):
         if hasattr(change, 'branch'):
-            if self.regex.match(change.branch):
+            if self.regex.fullmatch(change.branch):
                 return True
             return False
         return True