- Create a page with an Rollbacker (but Rollbacker is not Admin)
- Move the page with MalicousUser (to create a null revision)
- Revision delete/suppress the user of the null revision
- Use the rollback from action=history with Rollbacker and the "alreadyrolled" message shows "last edit of MalicousUser" and leak the revdeled user name of the null revision
Good points: The link to action=rollback contains a empty from and does not leak the name.
Bad points: The rollback link is useless, but provided (thats T6433 for move, but the link is also provided for other null revisions like import or protection) and should not be part of this task
Possible a regression from the refactor in https://gerrit.wikimedia.org/r/c/mediawiki/core/+/675236