Django commit…

Django commit https://github.com/django/django/commit/3647c0a49a2f4535b8a9aba40e662743e4d53e76 broke taggit. This commit fixes that. Thanks akaariai for the patch (see https://code.djangoproject.com/ticket/19399 for details).

taggit/managers.py

@@ -65,6 +65,7 @@ class TaggableManager(RelatedField, Field):
         return False
 
     def post_through_setup(self, cls):
+        self.related = RelatedObject(cls, self.model, self)
         self.use_gfk = (
             self.through is None or issubclass(self.through, GenericTaggedItemBase)
         )