Ticket #14170: get_language_from_request.diff

django/utils/translation/trans_real.py

@@ -369 +369 @@
         if normalized in _accepted:
             # We've seen this locale before and have an MO file for it, so no
             # need to check again.
-            return _accepted[normalized]
+            lang = _accepted[normalized]
+            if lang.lower() not in supported:
+                continue
 
         for lang, dirname in ((accept_lang, normalized),
                 (accept_lang.split('-')[0], normalized.split('_')[0])):