On 2008-06-10, Alain Desilets noticed on wiki-translation, that the English home page (Welcome to Wiki Translation) was considered to be in English by parts of the system, and Arabic by other parts of the system.
Below are exerpts from a chat session from that time
Looks like Welcome to Wiki-Translation is now considered to be Arabic!
If I go to the French page and click in the language pick list, I see that there is an Arabic version.
If I click on the Arabic version, I get to the English page.
If I click on Edit from the English page and look in the Language list, I see that it's English.
LPH confirmed that the language that a page is written in was stored redundantly in two places in the DB. He doesn't know why. Normally, those two languages should always be in synch, if they are only modified usign a function called updatePageLang(). But it seems that function is not always used.
We need to hunt down all the places where the language of a page is set without going through updatePageLang(). LPH suggested the following heuristics for finding such cases:
likely to be something that sets the "lang" field in tiki_pages or the "lang" field in tiki_translated_objects