Workflow.py: getCurrentStatusDict now return an empty dict when there is no workflow history.

product/ERP5Workflow/Document/Workflow.py

@@ -163,7 +163,7 @@ class Workflow(IdAsReferenceMixin("", "prefix"), XMLObject):
     # Copy is requested
     if workflow_history:
       return workflow_history[-1].copy()
-    return None
+    return {}
 
   def getDateTime(self):
     """