I think this is actually a data issue, not a bug in code. Over the last year, Launchpad removed identity management. Login, passwords, and email addresses are really managed by login.ubuntu.com. Ubuntu's login service provides the authentication to the wiki's mentioned in the bug comments. There may be a mismatch between the Ubuntu's data and the historic data in the wikis.
I think this is actually a data issue, not a bug in code. Over the last year, Launchpad removed identity management. Login, passwords, and email addresses are really managed by login.ubuntu.com. Ubuntu's login service provides the authentication to the wiki's mentioned in the bug comments. There may be a mismatch between the Ubuntu's data and the historic data in the wikis.