Lib/test/selfsigned_pythontestdotnet.pem in the cpython repository needs to be updated to match https://github.com/python/pythontestdotnet/blob/master/tls/self-signed-cert.pem, or the test fails :)

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ERROR: test_networked_good_cert (test.test_httplib.HTTPSTest)
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Traceback (most recent call last):
  File "/home/yen/tmp/cpython/Lib/test/test_httplib.py", line 1632, in test_networked_good_cert
    h.request('GET', '/')
  File "/home/yen/tmp/cpython/Lib/http/client.py", line 1221, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/home/yen/tmp/cpython/Lib/http/client.py", line 1267, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/home/yen/tmp/cpython/Lib/http/client.py", line 1216, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/home/yen/tmp/cpython/Lib/http/client.py", line 1004, in _send_output
    self.send(msg)
  File "/home/yen/tmp/cpython/Lib/http/client.py", line 944, in send
    self.connect()
  File "/home/yen/tmp/cpython/Lib/http/client.py", line 1383, in connect
    self.sock = self._context.wrap_socket(self.sock,
  File "/home/yen/tmp/cpython/Lib/ssl.py", line 405, in wrap_socket
    return self.sslsocket_class._create(
  File "/home/yen/tmp/cpython/Lib/ssl.py", line 853, in _create
    self.do_handshake()
  File "/home/yen/tmp/cpython/Lib/ssl.py", line 1117, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self signed certificate (_ssl.c:1055)