wireprotov1server: use binascii.unhexlify The "hex" codec doesn't exist in Python 3. We could use `codecs.decode(h, 'hex_codec')`. But `binascii.unhexlify()` exists and should work the same on Python 2 and 3. Differential Revision: https://phab.mercurial-scm.org/D5755

tests: conditionalize test-http-bad-server.t for Python 3.5 It appears that Python 3 introduced output buffering in the HTTP response stack. And Python 3.6 switched from sock.makefile().write() to sock.sendall(). So, we need to conditionalize test-http-bad-server.t to account for the difference in behavior between Python 3.5 and 3.6. Differential Revision: https://phab.mercurial-scm.org/D5754