Backport abompard's fix from Mailman 3.1.
The prototype archiver is not web-accessible. Therefore, the URL headers (Archived-At and List-Archives) should not be added for this archiver. Make its list_url() and permalink() methods return None.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
The prototype archiver is not web-accessible. Therefore, the URL headers (Archived-At and List-Archives) should not be added for this archiver. Make its list_url() and permalink() methods return None.