Our current code uses the ?action=render_ parameter to find out if a page is a redirect or not.

The new version of MediaWiki we're running breaks this by returning the actual page instead of a pointer.
http://wiki.musicbrainz.org/About_MusicBrainz?action=render
http://oldwiki.musicbrainz.org/About_MusicBrainz?action=render

This is fixed by adding &redirect=no to the request.
http://wiki.musicbrainz.org/About_MusicBrainz?action=render&redirect=no