WorkflowTool.py: deal the case when actbox_url is an empty string.

product/ERP5/Tool/WorkflowTool.py

@@ -326,7 +326,7 @@ class WorkflowTool(BaseTool, OriginalWorkflowTool):
           transition.setActboxName(tdef.actbox_name)
           # alter actbox_url to gain compatibility of erp5 workflow
           compatible_url = tdef.actbox_url
-          if compatible_url is not None:
+          if compatible_url is not '':
             index_action_id = compatible_url.find(tdef.id)
             compatible_url = compatible_url[:index_action_id] + 'transition_' + compatible_url[index_action_id:]
             transition.setActboxUrl(compatible_url)
@@ -414,6 +414,7 @@ class WorkflowTool(BaseTool, OriginalWorkflowTool):
                 state_id_list.append(state_id)
               worklist.setMatchedSimulationStateList(state_id_list)
               # alter url:
+              if qdef.actbox_url is not '':
                 compatible_url = qdef.actbox_url
                 index_state_id = compatible_url.find(value)
                 compatible_url = compatible_url[:index_state_id] + 'state_' + compatible_url[index_state_id:]
@@ -425,6 +426,7 @@ class WorkflowTool(BaseTool, OriginalWorkflowTool):
                 state_id_list.append(state_id)
               worklist.setMatchedValidationStateList(state_id_list)
               # alter url:
+              if qdef.actbox_url is not '':
                 compatible_url = qdef.actbox_url
                 index_state_id = compatible_url.find(value)
                 compatible_url = compatible_url[:index_state_id] + 'state_' + compatible_url[index_state_id:]