WorkflowTool.py: improve a type getter.

product/ERP5/Tool/WorkflowTool.py

@@ -587,9 +587,9 @@ class WorkflowTool(BaseTool, OriginalWorkflowTool):
     # in the action list. Reassignment happens in the background. Nothing need to
     # be done, just go back to whatever you are doing.
     type_workflow_dict = self.getChainsByType()
-
+    type_tool = self.getPortalObject().portal_types
     for ptype_id in type_workflow_dict:
-      ptype = getattr(context.getPortalObject().portal_types, ptype_id, None)
+      ptype = type_tool._getOb(ptype_id, None)
       if ptype is not None:
         for workflow_id in type_workflow_dict[ptype_id]:
           workflow = getattr(self, workflow_id, None)