[PyQt] How to avoid "QTextCodec::~QTextCodec: Called by application"?

[DDGG]

I have a codec class:

# gb18030.py
from PyQt4 import QtCore

class QGb18030Codec(QtCore.QTextCodec):
   def __init__(self):
       QtCore.QTextCodec.__init__(self)

   def name(self):
       return "GB18030"

   def aliases(self):
       return []

   def mibEnum(self):
       return 114

   def convertToUnicode(self, chars, len):
       ...

   def convertFromUnicode(self, uc, len, state):
       ...

gb18030 = QGb18030Codec()

# end

After i have run it, i got a notice message in my console window:
QTextCodec::~QTextCodec: Called by application
How to avoid this message?
Thanks!