Py.test errors, webpage keeps on loading

test/mitmproxy/test_server.py .....................................----------------------------------------
Error in processing of request from 127.0.0.1:54207
Traceback (most recent call last):
  File "/home/ujjwal/mitmproxy/mitmproxy/net/tcp.py", line 932, in connection_thread
    self.handle_client_connection(connection, client_address)
  File "/home/ujjwal/mitmproxy/pathod/pathod.py", line 389, in handle_client_connection
    h.handle()
  File "/home/ujjwal/mitmproxy/pathod/pathod.py", line 257, in handle
    alpn_select=self.server.ssloptions.alpn_select,
  File "/home/ujjwal/mitmproxy/mitmproxy/net/tcp.py", line 871, in convert_to_ssl
    **sslctx_kwargs)
  File "/home/ujjwal/mitmproxy/mitmproxy/net/tcp.py", line 838, in create_ssl_context
    context.use_certificate(cert.x509)
  File "/home/ujjwal/mitmproxy/venv3.5/lib/python3.5/site-packages/OpenSSL/SSL.py", line 610, in use_certificate
    _raise_current_error()
  File "/home/ujjwal/mitmproxy/venv3.5/lib/python3.5/site-packages/OpenSSL/_util.py", line 48, in exception_from_error_queue
    raise exception_type(errors)
OpenSSL.SSL.Error: [('SSL routines', 'SSL_CTX_use_certificate', 'ee key too small')]

----------------------------------------

test/pathod/test_pathoc.py ..............Exception in thread WebsocketFrameReader:
Traceback (most recent call last):
  File "/usr/lib/python3.5/threading.py", line 914, in _bootstrap_inner
    self.run()
  File "/home/ujjwal/mitmproxy/pathod/pathoc.py", line 129, in run
    r, _, _ = select.select([self.rfile], [], [], 0.05)
ValueError: file descriptor cannot be a negative integer (-1)

.......

These 2 errors come when I run py.test. Also, when I run mitmproxy it doesn’t show any flows but the webpage keeps on showing the loading sign in browser.

I’m using Kali 2016.2 and running the source code from github in venv.
Kali also has an older version 0.17.1 which works fine.