If I understand correctly, this important fix for CHttpRequest regarding proper processing of Accept-Language header, was rolled back lately by this commit. As a result there is the same old buggy implementation in the master right now. The only minor problem with the former fix was that it mentioned undefined variable $pref, which can be completely eliminated without any impact on the improvement that that code introduced.
If it’s so, shouldn’t the issue with incorrect language sorting be fixed anew?