requests.post fail inside of django shell but not python shell

[paulfab]

When I execute :
requests.post("​https://slack.com/api/chat.postMessage", data= {"channel": "maison"})
it fails in the django shell (python manage.py shell) with the error :

InvalidCodepoint: Codepoint U+002A at position 1 of u'*' not allowed

but it doesnt fail in the python shell
So this tells me it is probable something Django related
It was working before, and the only thing I changed is that I updated the SSL certificate of my server

Thanks

complete trace of the error is :

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/requests/api.py", line 107, in post
    return request('post', url, data=data, json=json, **kwargs)
  File "/usr/lib/python2.7/dist-packages/requests/api.py", line 53, in request
    return session.request(method=method, url=url, **kwargs)
  File "/usr/lib/python2.7/dist-packages/requests/sessions.py", line 468, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/lib/python2.7/dist-packages/requests/sessions.py", line 576, in send
    r = adapter.send(request, **kwargs)
  File "/usr/lib/python2.7/dist-packages/requests/adapters.py", line 376, in send
    timeout=timeout
  File "/usr/local/lib/python2.7/dist-packages/urllib3/connectionpool.py", line 594, in urlopen
    chunked=chunked)
  File "/usr/local/lib/python2.7/dist-packages/urllib3/connectionpool.py", line 350, in _make_request
    self._validate_conn(conn)
  File "/usr/local/lib/python2.7/dist-packages/urllib3/connectionpool.py", line 833, in _validate_conn
    conn.connect()
  File "/usr/local/lib/python2.7/dist-packages/urllib3/connection.py", line 324, in connect
    cert = self.sock.getpeercert()
  File "/usr/local/lib/python2.7/dist-packages/urllib3/contrib/pyopenssl.py", line 312, in getpeercert
    'subjectAltName': get_subj_alt_name(x509)
  File "/usr/local/lib/python2.7/dist-packages/urllib3/contrib/pyopenssl.py", line 185, in get_subj_alt_name
    for name in ext.get_values_for_type(x509.DNSName)
  File "/usr/local/lib/python2.7/dist-packages/urllib3/contrib/pyopenssl.py", line 141, in _dnsname_to_stdlib
    name = idna.encode(name)
  File "/usr/lib/python2.7/dist-packages/idna/core.py", line 354, in encode
    result.append(alabel(label))
  File "/usr/lib/python2.7/dist-packages/idna/core.py", line 275, in alabel
    check_label(label)
  File "/usr/lib/python2.7/dist-packages/idna/core.py", line 252, in check_label
    raise InvalidCodepoint('Codepoint {0} at position {1} of {2} not allowed'.format(_unot(cp_value), pos+1, repr(label)))
InvalidCodepoint: Codepoint U+002A at position 1 of u'*' not allowed