Fixed #7831: be case-insensitive when in `get_language_from_request`.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8561 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/utils/translation/trans_real.py

@@ -381,7 +381,7 @@ def get_language_from_request(request):
 
         for lang, dirname in ((accept_lang, normalized),
                 (accept_lang.split('-')[0], normalized.split('_')[0])):
-            if lang not in supported:
+            if lang.lower() not in supported:
                 continue
             langfile = os.path.join(globalpath, dirname, 'LC_MESSAGES',
                     'django.mo')