In the mediawiki/extensions/EventBus repository, there's a class called EventBusHooks, that has a function, onArticleRevisionVisibilitySet, which likely unintentionally creates new global functions.
In PHP, creating a function inside a class static function actually creates a global function (unlike JavaScript). https://3v4l.org/7tNtb
This should be switched to having private static helper functions instead of creating new global functions.
I'll mentor this for Google-Code-in-2017