According to those back traces, the server has apparently already handled one request and is waiting for a second request. However the client is still waiting for a response from its original request.

Some things I might try would be to disable the server, and make my own dummy server to see if it responds to that. Similarly, disable the client and manually make a request to the server and see what the response is. On Linux the “socat” or “netcat” programs are useful for this stuff, or you can just use the Python interactive interpreter to create a socket and send and receive.

Client connection is made at <https://hg.python.org/cpython/file/v3.5.0/Lib/test/test_httpservers.py#l252>. Server is constructed at <https://hg.python.org/cpython/file/v3.5.0/Lib/test/test_httpservers.py#l42>.

You could also try adding self.con.set_debuglevel(99) to the test_get() method, though I suspect it will just output the request sent, and not report any reply or headers. In my case the test works, and I see:

send: b'GET / HTTP/1.1\r\nHost: 127.0.0.1:48059\r\nAccept-Encoding: identity\r\n\r\n'
reply: 'HTTP/1.1 200 OK\r\n'
[Unit test output]
header: Server header: Date $