fix queryset tests

tests/queryset/queryset.py

@@ -970,7 +970,10 @@ class QuerySetTest(unittest.TestCase):
         org = Organization.objects.get(id=o1.id)
         with query_counter() as q:
             org.save(cascade=False)
-            self.assertEqual(q, 0)
+            if mongodb_version >= (3, 0):
+                self.assertEqual(q, 1)
+            else:
+                self.assertEqual(q, 0)
 
         # Saving a doc after you append a reference to it should result in
         # two db operations (a query for the reference and an update).