Last modified: 2013-11-19 15:20:15 UTC
I noticed this on the English Wikipedia, where the actual Mediawiki version is 1.22wmf12 (bbaecbc). I tried to view the messages from a private filter which I didn't have permission to view. Instead of an error message, messages from other filters were shown, as though I had left "Filter ID:" blank on the form. Special:AbuseFilter says "You may not view details of this filter because it is hidden from public view." A message like that would be far less confusing.
Special:AbuseLog is part of the AbuseFilter extension -> moving