Stephen Smoogen has opened a bug about the license in CSS Janus. This needs wider discussion, though, so I'm copying it here.
I am the maintainer of the mediawiki package for Fedora EPEL project. While putting together the package for 1.19 it was found that the license to maintenance/cssjanus is ASL 2.0 and the license for mediawiki is GPL+2.0. The GPL 2. and ASL 2. are not "compatible" to the FSF so I am trying to work out my options and to find out what the mediawiki's projects rationale for bundling the two items together.
1) cssjanus has a GPL exception to its ASL license that mediawiki knows of.
2) we need to look at mediawiki being used as GPL 3.0 even though it is not explicitely licensed that way.
I'll point the bug to the on-list discussion, so please follow up here.