I tested metode urllib2.read() on 2000 web_pages and there was a
exception ValueError in only one case, here is short code:

import urllib2
req = urllib2.urlopen('http://www.peachbit.org/')
req.read()


Traceback (most recent call last):
  File "httplib_bug.py", line 6, in <module>
    req.read()
  File "/usr/lib/python2.5/socket.py", line 291, in read
    data = self._sock.recv(recv_size)
  File "/usr/lib/python2.5/httplib.py", line 509, in read
    return self._read_chunked(amt)
  File "/usr/lib/python2.5/httplib.py", line 548, in _read_chunked
    chunk_left = int(line, 16)
ValueError: invalid literal for int() with base 16: ''