Fixed #15103 - SuspiciousOperation with limit_choices_to and raw_id_fields

Thanks to natrius for the report.

This patch also fixes some unicode bugs in affected code.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15347 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/options.py

@@ -55,6 +55,10 @@ class Options(object):
         self.abstract_managers = []
         self.concrete_managers = []
 
+        # List of all lookups defined in ForeignKey 'limit_choices_to' options
+        # from *other* models. Needed for some admin checks. Internal use only.
+        self.related_fkey_lookups = []
+
     def contribute_to_class(self, cls, name):
         from django.db import connection
         from django.db.backends.util import truncate_name