Board Thread:General Coding Help/@comment-29826282-20161230193523/@comment-1757994-20170103040546

Wikia has already forked the majority of the code they run, because they decided to stabilize on mw1.19 and customize the rest. Constantly updating to the latest software with forward-porting all their custom modifications was getting to be too much for them.

At some point back-porting newer code to be compatible with their "stable" base would, I think, also get to be too much. Maybe this is one example of it.

In the meantime, their strategic direction appears to be to make wiki software utterly different from MediaWiki, but based on what was once a version of MediaWiki. If it continues, you should discard any expectation that any user-written code will necessarily be portable between Wikia and current MediaWiki versions.