check we have uid to delete before calling sql method

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@11732 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/CMFActivity/Activity/SQLDict.py

@@ -338,6 +338,7 @@ class SQLDict(RAMDict):
         uid_list = uid_list_list[i]
         priority = priority_list[i]
         if m.is_executed:
+          if len(uid_list) > 0:
             activity_tool.SQLDict_delMessage(uid = uid_list)                # Delete it
           get_transaction().commit()                                        # If successful, commit
           if m.active_process: