r78013 removes key 'december' from MessagesDe_at.php, but on de.wp the message [[de:MediaWiki:December/de-at]] is not updated to the fallback.
The sync has work for other messages like [[de:MediaWiki:Htmlform-submit]] (r78138)
It is possible to update the message to the fallback, when it is removed from Message.php? Thanks
Version: unspecified
Severity: enhancement