[Mediawiki-i18n] I18n of system messages horribly broken in multilanguage wikis since some months

[Daniel Arnold]

Hi folks,

I know the summary line sounds quite lurid but this is really true and thatfor 
I'd like to have your attention and feedback on that matter.

You can find the following analysis of the problem as well at: 
http://bugzilla.wikimedia.org/show_bug.cgi?id=8188

Some time ago the I18n system of MediaWiki worked in multilanguage wikis like 
Wikimedia Commons the following way:
 * Look if there is a localised English message at the corresponding MediaWiki 
namespace page (directly in SQL database, not transcluded from I18n-file) 
regardless of the user language setting.
 * If the english message string is existing in the MediaWiki namespace don't 
use the transcluded I18n-file for that message in any language but only the 
corresponding /<ISO-CODE> sub page if it is directly existing.
 * If that page is not existing fall back to the English message
 * If neither the english message nor the translated message exists in the 
MediaWiki namespace use the transcluded string from the I18n file.
 
Since some months MediaWiki works the following way:
 * If the specific localised message is not existing in MediaWiki namespace 
take the transcluded message from the I18n-file.
 
This is one of the worst UI changes we just realised by random in Commons, 
seriously. We did heavily rely on the old behavior. If a message wasn't 
existing in the database, the user got the english one. Fine. The changes on 
important UI messages were easy to follow and were an acceptable amount of 
work. We didn't need to fear that people did get any totally useless UI 
messages if they did choose a less common language none of us admins was able 
to speak.
 
Until we realised the change that 
http://commons.wikimedia.org/wiki/Special:Upload did show just useless info 
and nothing what is absolutely crucial to remind during upload if you did 
have a less common language setting it took several months (the corresponding 
default message MediaWiki:Uploadtext/<ISO-code> from I18n-files is totally 
useless in Commons). Within that period many people did upload a lot of 
copyvios simply because they were not able knowing it better.
 
The result of that severe bug was this huge 
overwrite-quick-and-dirty-work-around for this single upload message only: 
http://commons.wikimedia.org/w/index.php?offset=&limit=50&target=Arnomane&title=Special%3AContributions&namespace=8 
(all messages with the "in order to supress a inadequate default mediawiki 
message" change comment).
 
There are much more important MediaWiki messages existing that would need such 
a time consuming and painfull hack ASAP.

So please look at the bugzilla report for further information and on ideas on 
how to solve that bug.

As well do you know which software change did cause this to happen?
 
Cheers, Arnomane