PTFE-1927 add full test with lonely stab

bert_e/tests/test_bert_e.py

@@ -4951,6 +4951,18 @@ def test_dev_major_only(self):
                 'origin/stabilization/4.3.18'
             )
 
+    def test_dev_major_lonely_stab(self):
+        """Test Bert-E's handling of a lonely stabilization/x.y.z branch."""
+        # create a stabilization 4.5.2 branch from development/4
+        self.gitrepo.cmd('git fetch')
+        self.gitrepo.cmd('git checkout -b stabilization/4.5.2 origin/development/4')
+        self.gitrepo.cmd('git push -u origin stabilization/4.5.2')
+        # create a PR from the stabilization branch
+        pr = self.create_pr('bugfix/TEST-01', 'stabilization/4.5.2')
+        # expect a DevBranchDoesNotExist exception
+        with self.assertRaises(exns.DevBranchDoesNotExist):
+            self.handle(pr.id, options=self.bypass_all, backtrace=True)
+
 
 class TestQueueing(RepositoryTests):
     """Tests which validate all things related to the merge queue.