A patch[1] was recently merged which adjusts the changes required when
adding or removing classes from mediawiki core.
Rather than manually adjusting the map from classname to filename in
includes/AutoLoad.php developers now need only run the
maintenance/generateLocalAutoload.php script. This script will scan
mediawiki core and output an equivalent map from classname => filename to
autoload.php in the root of the repository.
Erik B.
[1]
https://gerrit.wikimedia.org/r/163304