Return list of messages as this way result can be used with an Active Process more easily.

bt5/erp5_crm/ExtensionTemplateItem/CRMMigration.py

@@ -62,5 +62,5 @@ def migrateEventWorkflowHistory(self):
     return
   workflow_tool = portal.portal_workflow
   workflow_tool._jumpToStateFor(self, new_state)
-  return 'Event workflow migration on %s : %s -> %s' % (
-      self.getPath(), current_state, new_state)
+  return ['Event workflow migration on %s : %s -> %s' % (
+      self.getPath(), current_state, new_state)]

bt5/erp5_crm/bt/revision

-580
\ No newline at end of file
+581
\ No newline at end of file