Ticket #14467: fix_for_None_values.diff

django/contrib/admin/views/main.py

@@ -187 +187 @@
                 else:
                     lookup_params[key] = True
 
+            if value == 'None':
+                lookup_params[key] = None
+
         # Apply lookup parameters from the query string.
         try:
             qs = qs.filter(**lookup_params)