Prove that LP: #1165589 doesn't affect Mailman 3
This bug doesn't affect MM3. Add a test to prove this. Drive-by typo fix. Only apply this to MM3.1 since there's no bug here.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
This bug doesn't affect MM3. Add a test to prove this. Drive-by typo fix. Only apply this to MM3.1 since there's no bug here.