Mask dependent config errors

When a change to an untrusted project depends on a change to a
config project, we can validate that the resulting config will be
correct, but we can't use it.  Currently, in that case, we report
the configuration "error" that results from not using the
dependent config-project change.  Instead, leave a message for the
user saying that everything will be okay if they wait for that
change to merge.

Change-Id: I34a002000d1bf640b298b7bf72d1af5a3a72ced1
diff --git a/tests/unit/test_v3.py b/tests/unit/test_v3.py
index 327d457..fbc629b 100755
--- a/tests/unit/test_v3.py
+++ b/tests/unit/test_v3.py
@@ -731,6 +731,47 @@
         self.assertIn('the only project definition permitted', A.messages[0],
                       "A should have a syntax error reported")
 
+    def test_untrusted_depends_on_trusted(self):
+        with open(os.path.join(FIXTURE_DIR,
+                               'config/in-repo/git/',
+                               'common-config/zuul.yaml')) as f:
+            common_config = f.read()
+
+        common_config += textwrap.dedent(
+            """
+            - job:
+                name: project-test9
+            """)
+
+        file_dict = {'zuul.yaml': common_config}
+        A = self.fake_gerrit.addFakeChange('common-config', 'master', 'A',
+                                           files=file_dict)
+        in_repo_conf = textwrap.dedent(
+            """
+            - job:
+                name: project-test1
+            - project:
+                name: org/project
+                check:
+                  jobs:
+                    - project-test9
+            """)
+
+        file_dict = {'zuul.yaml': in_repo_conf}
+        B = self.fake_gerrit.addFakeChange('org/project', 'master', 'B',
+                                           files=file_dict)
+        B.data['commitMessage'] = '%s\n\nDepends-On: %s\n' % (
+            B.subject, A.data['id'])
+        self.fake_gerrit.addEvent(B.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        self.assertEqual(B.data['status'], 'NEW')
+        self.assertEqual(B.reported, 1,
+                         "B should report failure")
+        self.assertIn('depends on a change to a config project',
+                      B.messages[0],
+                      "A should have a syntax error reported")
+
     def test_duplicate_node_error(self):
         in_repo_conf = textwrap.dedent(
             """