gwibber doesn't support http proxy

[Lionel Dricot]

When using a proxy set up in gnome preferences, gwibber just fail to connect to identi.ca and twitter :

Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/gwibber/microblog/__init__.py", line 46, in get_data
    for message in method(client):
  File "/usr/lib/python2.6/dist-packages/gwibber/microblog/twitter.py", line 217, in receive
    for data in self.get_messages():
  File "/usr/lib/python2.6/dist-packages/gwibber/microblog/twitter.py", line 166, in get_messages
    urllib.urlencode({"count": self.account["receive_count"] or "20"})))
  File "/usr/lib/python2.6/dist-packages/gwibber/microblog/twitter.py", line 161, in connect
    url, data, headers = {"Authorization": self.get_auth()})).read()
  File "/usr/lib/python2.6/urllib2.py", line 124, in urlopen
    return _opener.open(url, data, timeout)
  File "/usr/lib/python2.6/urllib2.py", line 383, in open
    response = self._open(req, data)
  File "/usr/lib/python2.6/urllib2.py", line 401, in _open
    '_open', req)
  File "/usr/lib/python2.6/urllib2.py", line 361, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.6/urllib2.py", line 1138, in https_open
    return self.do_open(httplib.HTTPSConnection, req)
  File "/usr/lib/python2.6/urllib2.py", line 1105, in do_open
    raise URLError(err)
URLError: <urlopen error [Errno 1] _ssl.c:480: error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol>

(in my case, it looks like gwibber is trying to use the default proxy of the network which is not the one I want to use and not the one set in gnome preferences)