This is to inform the core team that most non-WMF-maintained skins are
broken since 1.36-wmf.5 to the extent of not loading any stylesheets. As
these skins are in use by many operators, this unintended change would
cause serious disruption. The Stable interface policy
<https://www.mediawiki.org/wiki/Stable_interface_policy#Removal> is
supposed to prevent this, but this error went unnoticed.
I've submitted the necessary patch to prevent this:
https://gerrit.wikimedia.org/r/c/mediawiki/core/+/622254
https://phabricator.wikimedia.org/T266735
Demian