I spent way too long looking for MediaWiki’s version information. Most applications store the version info in a file or in the database. MediaWiki is a HUGE mess of code and database. I finally found it in a file. It’s in includes/DefaultSettings.php and is stored as a variable – wgVersion. This is for post 1.3.7 versions of MediaWiki, perhaps even earlier versions.
I write this here because no amount of searching turned up this information. I found it through a series of lucky greps. So, to help out in Google searches:
where is MediaWiki’s version information stored?
locate MediaWiki’s version info
MediaWiki version file
MediaWiki version info