Cannot update a ticket while changing child ticket to patent ticket(and vice versa) with a 'comment'.

[anonymous]

While changing child ticket to parent ticket in a ticket ,If we give some comment and submit both then there is no update in ticket and There is Integrity Error

IntegrityError: columns ticket, time, field are not unique

File "C:/SDWorkbenchServer/python/lib/site-packages/trac-0.12.2-py2.7.egg/trac/web/main.py", line 511, in _dispatch_request

dispatcher.dispatch(req)

File "C:/SDWorkbenchServer/python/lib/site-packages/trac-0.12.2-py2.7.egg/trac/web/main.py", line 237, in dispatch

resp = chosen_handler.process_request(req)

File "C:/SDWorkbenchServer/python/lib/site-packages/trac-0.12.2-py2.7.egg/trac/ticket/web_ui.py", line 169, in process_request

return self._process_ticket_request(req)

File "C:/SDWorkbenchServer/python/lib/site-packages/trac-0.12.2-py2.7.egg/trac/ticket/web_ui.py", line 541, in _process_ticket_request

self._do_save(req, ticket, action)

File "C:/SDWorkbenchServer/python/lib/site-packages/trac-0.12.2-py2.7.egg/trac/ticket/web_ui.py", line 1238, in _do_save

cnum=internal_cnum):

File "C:/SDWorkbenchServer/python/lib/site-packages/trac-0.12.2-py2.7.egg/trac/ticket/model.py", line 360, in save_changes

listener.ticket_changed(self, comment, author, old_values)

File "C:/SDWorkbenchServer/python/lib/site-packages/tracmastertickets-3.0.2-py2.7.egg/mastertickets/api.py", line 120, in ticket_changed

links.save(author, comment, tkt.time_changed, db)

File "C:/SDWorkbenchServer/python/lib/site-packages/tracmastertickets-3.0.2-py2.7.egg/mastertickets/model.py", line 83, in save

(n, when_ts, author, 'comment', , '(In #%s) %s'%(self.tkt.id, comment)))

File "C:/SDWorkbenchServer/python/lib/site-packages/trac-0.12.2-py2.7.egg/trac/db/util.py", line 65, in execute

return self.cursor.execute(sql_escape_percent(sql), args)

File "C:/SDWorkbenchServer/python/lib/site-packages/trac-0.12.2-py2.7.egg/trac/db/sqlite_backend.py", line 78, in execute

result = PyFormatCursor.execute(self, *args)

File "C:/SDWorkbenchServer/python/lib/site-packages/trac-0.12.2-py2.7.egg/trac/db/sqlite_backend.py", line 56, in execute

args or [])

File "C:/SDWorkbenchServer/python/lib/site-packages/trac-0.12.2-py2.7.egg/trac/db/sqlite_backend.py", line 48, in _rollback_on_error

return function(self, *args, kwargs)