I'd like to offer help if it's needed for this; I'm a php coder, as I maintain the custom skin and several customized extensions for DoomWiki.org. I'd have to be given temporary access to the server with sufficient rights to modify any of the MediaWiki components, however. This seems like a relatively simple issue that should be patchable in a few minutes to an hour, though, I'd heavily recommend upgrading to a newer MediaWiki as soon as it is practical, as 1.21.1 is no longer supported to any degree.