(bug 5665 comment 6)
(In reply to comment #5)
We've had deleteDefaultMessages.php for ages, marking WORKSFORME.
The way that script has been implemented it only deletes pages
from the MediaWiki namespace that were created by old the MediaWiki
It doesn't delete pages that are redundant but last modified by a
local user. This is very common on lang wikis created after 2006
(when we last used the "MediaWiki_default" thing in the installer)
but were not handled by translatewiki.net yet.
Those wikis have 100s of local pages with translations. Most of
which have been since imported to translatewiki and as such are
Keeping them local only causes translations to get outdated and/or
cause migration issues when messages change (e.g. different
parameters or whatever).