WorkflowTool.py: during conversion, Guard's expression keep none if old guard...

WorkflowTool.py: during conversion, Guard's expression keep none if old guard didn't have expression.

product/ERP5/Tool/WorkflowTool.py

@@ -326,7 +326,6 @@ class WorkflowTool(BaseTool, OriginalWorkflowTool):
             transition.setGroupList(tdef.guard.groups)
             if tdef.guard.expr is not None:
               transition.setExpression(tdef.guard.expr.text)
-            else: transition.setExpression('')
         # create states (portal_type = State)
         for sid in dc_workflow.states:
           sdef = dc_workflow.states.get(sid)
@@ -415,7 +414,8 @@ class WorkflowTool(BaseTool, OriginalWorkflowTool):
             worklist.setRoleList(qdef.guard.roles)
             worklist.setPermissionList(qdef.guard.permissions)
             worklist.setGroupList(qdef.guard.groups)
-            worklist.setExpression(qdef.guard.expr)
+            if qdef.guard.expr is not None:
+              worklist.setExpression(qdef.guard.expr.text)
       else:
         for tid in dc_workflow.interactions:
           interaction = workflow.newContent(portal_type='Interaction', temp_object=temp)
@@ -456,7 +456,6 @@ class WorkflowTool(BaseTool, OriginalWorkflowTool):
             interaction.setGroupList(tdef.guard.groups)
             if tdef.guard.expr is not None:
               interaction.setExpression(tdef.guard.expr.text)
-            else: interaction.setExpression('')
           interaction.setPortalTypeFilter(tdef.portal_type_filter)
           interaction.setPortalTypeGroupFilter(tdef.portal_type_group_filter)
           if interaction.portal_type_filter == ():