tests: change how sockets are closed Python 3 uses a different type to represent a socket file object than Python 2. We need to conditionalize how the socket is closed accordingly. While we're here, we switch to use socket.shutdown() to close the socket. This is because socket.close() may not actually close the socket until it is GCd. socket.shutdown() forces an immediate shutdown. I suspect Python 3 changed semantic behavior here, as I can't get test-http-bad-server.t to work with socket.close(). socket.shutdown() does appear to work, however. Differential Revision: https://phab.mercurial-scm.org/D5751