Fix issue causing failure

This was supposed to be fixed with the cherry-pick but I must have done
something wrong.  I expect a conflict on a merge as we pull these things
together.

pywbem_mock/_wbemconnection_mock.py

@@ -465,7 +465,7 @@ def compile_mof_string(self, mof_str, namespace=None, search_paths=None,
         """
 
         if namespace is None:
-            namespace = DEFAULT_NAMESPACE
+            namespace = self.default_namespace
 
         # TODO:ks Future we might be able to use our own MOFWBEMRepository to
         # directly insert into our repository instead of copying them