In python2.3, the following code works.  In python2.4
it fails with an AttributeError:

>>> import urllib2
>>> request = urllib2.Request("http://pheared.net")
>>> opener = urllib2.build_opener()
>>> r = opener.open(request)
>>> r.fileno()
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/lib/python2.4/socket.py", line 246, in fileno
    return self._sock.fileno()
AttributeError: HTTPResponse instance has no attribute
'fileno'

Without a fileno it's hard to do things like select.