Any suggestions how to stay up to date about
modifications on the
mediawiki code?
If you want to stay up-to-date with modifications in between official
releases, I think your best option is to subscribe to the SVN mailing
list which emails you every time someone modifies the code
(instructions on
mediawiki.org). Beware, however, that there are a
*lot* of modifications made (many of them just updating language
files, but you get an email anyway). Also, using code which isn't an
official release means you are testing possibly extremely buggy code
and it isn't recommended for real world usage (it generally works
fine, and major bugs are fixed pretty quickly, but there are no
guarantees).
That said, I don't think what you're seeing is a change in code. I
think it's just a configuration option in LocalSettings.php, I can't
remember what it's called, though.