title: unexpected pyssl certificate error
body: <p>I'm writing a small SSL proxy server and keep getting <code>ssl.SSLError: [SSL: SSLV3_ALERT_CERTIFICATE_UNKNOWN] sslv3 alert certificate unknown (_ssl.c:661)</code> from an android app client but not a browser. I did set <code>ssl.CERT_NONE</code>. Here is my test code:</p>
  
  <pre><code>SSLcontext = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
  SSLcontext.load_cert_chain('server.crt', 'server.key')
  SSLcontext.verify_mode = ssl.CERT_NONE
  SSLcontext.check_hostname = False
  
  s = socket.socket()
  s.bind(('127.0.0.1', 443))
  s.listen(5)
  
  c = s.accept()[0]
  c = SSLcontext.wrap_socket(c, server_side = True)
  print c.recv(1024)
  </code></pre>
  
  <p>Is this because of certificate pinning on the android app or I'm doing something wrong ?</p>