ci(tracker): require one metadata owner per pull request

tests/unit/test_tracker_policy.py

@@ -47,7 +47,21 @@ class TestCheckPullRequest(unittest.TestCase):
         self.assertIn("either have a label or reference an issue", errors[0])
         api.request.assert_not_called()
 
-    def test_validates_issue_reference_even_when_pr_is_labelled(self):
+    def test_rejects_labelled_pr_linked_to_real_issue(self):
+        api = Mock()
+        api.request.return_value = {"number": 12, "pull_request": None}
+        event = {
+            "pull_request": {
+                "title": "Change",
+                "body": "Closes #12",
+                "labels": [{"name": "Kind/Documentation"}],
+            }
+        }
+        errors = check_pull_request(event, api)
+        self.assertEqual(len(errors), 1)
+        self.assertIn("exactly one tracking mode", errors[0])
+
+    def test_still_validates_issue_reference_when_both_modes_are_used(self):
         api = Mock()
         api.request.return_value = {"number": 12, "pull_request": {}}
         event = {
@@ -58,8 +72,9 @@ class TestCheckPullRequest(unittest.TestCase):
             }
         }
         errors = check_pull_request(event, api)
-        self.assertEqual(len(errors), 1)
-        self.assertIn("not an issue", errors[0])
+        self.assertEqual(len(errors), 2)
+        self.assertIn("exactly one tracking mode", errors[0])
+        self.assertIn("not an issue", errors[1])
 
 
 class TestEnsureIssueLabel(unittest.TestCase):