Fixed #7163 -- Fixed a translation-sharing problem so that you can have en-gb

and en-us at the app-level, even though Django only has an "en" translation
(for example). Analysis and patch from ognjen.maric@gmail.com.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@7857 bcc190cf-cafb-0310-a4f2-bffc1f526a37