hooks: add more bad Bug: test cases

Bug: None
Test: unittests pass
Change-Id: I92a509e9c0d9db00609c00311695a9dc916993b9
diff --git a/rh/hooks_unittest.py b/rh/hooks_unittest.py
index 8f74d17..4510c6e 100755
--- a/rh/hooks_unittest.py
+++ b/rh/hooks_unittest.py
@@ -339,6 +339,8 @@
                 'subj',
                 'subj\n\nBUG=1234\n',
                 'subj\n\nBUG: 1234\n',
+                'subj\n\nBug: N/A\n',
+                'subj\n\nBug:\n',
             ))
 
     def test_commit_msg_changeid_field(self, _mock_check, _mock_run):