must return the right variable name

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@13858 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/tests/ERP5TypeTestCase.py

@@ -506,10 +506,11 @@ class ERP5TypeTestCase(PortalTestCase):
       self.assertRaises(ValidationFailed, self.workflow_tool.doActionFor, object, transition_id, wf_id=workflow_id)
       workflow_history = self.workflow_tool.getInfoFor(ob=object, name='history', wf_id=workflow_id)
       self.assertEqual(len(workflow_history), reference_history_length + 1)
+      workflow_error_message = str(workflow_history[-1]['error_message'])
       if error_message is not None:
-        self.assertEqual(str(workflow_history[-1]['error_message']), error_message)
+        self.assertEqual(workflow_error_message, error_message)
       self.assertEqual(object.getSimulationState(), reference_workflow_state)
-      return error_message
+      return workflow_error_message
 
 def setupERP5Site( business_template_list=(),
                    app=None,