Ticket #2160: 0_pk.patch

django/db/models/base.py

@@ -167 +167 @@
 
         # First, try an UPDATE. If that doesn't update anything, do an INSERT.
         pk_val = self._get_pk_val()
-        pk_set = bool(pk_val)
+        pk_set = bool(pk_val) or pk_val == 0
         record_exists = True
         if pk_set:
             # Determine whether a record with the primary key already exists.