let s='\xff\n' 
The expected result of s.decode('gb2312', 'ignore') is u"\n", while in 2.6.6 it is u"".
  s can be replaced with chr(m) + chr(n) , where m is in range of 128~255, and n in 0~127.
  In the above cases, try decoding from chr(n) will never interfere with later parts in the string if there is any, since chr(n) do not start a multibyte sequence.