from urllib2 import *
req = Request("http://someurl/page.html",
headers={'range: bytes=%s':'20-40'})
result = urlopen(req)

will die with something like :
  File "/usr/lib/python2.3/urllib2.py", line 306, in
_call_chain
    result = func(*args)
  File "/usr/lib/python2.3/urllib2.py", line 412, in
http_error_default
    raise HTTPError(req.get_full_url(), code, msg,
hdrs, fp)
urllib2.HTTPError: HTTP Error 206: Partial Content


line 892 in {PATH}/urllib2.py should be changed from :
if code == 200:
to
if code in [200, 206]:

peace