Last modified: 2013-11-05 14:50:49 UTC
If a user makes some edits, then a restore of an old edit, and then a sysop does a rollback, the later rollback will fail but says "Action complete". It seems like the restore must be done on someone others edits, not on the users own edits.
The bug only hits when a restore is done on somebody else's edit.
There is only a missing message about an empty diff/patch.
*** This bug has been marked as a duplicate of bug 45226 ***