There is just one test failure on darwin, and it can probably be worked
around by allowing local networking.
This should hopefully fix the following testsuite error:
```
___________________________ test_timeout_subsequent ____________________________
tests/test_other.py:137: in test_timeout_subsequent
assert response.status == 200
E assert 408 == 200
E +408
E -200
Handler = <class 'tests.test_other.test_timeout_subsequent.<locals>.Handler'>
_ = b'Request Timeout'
http = <httplib2.Http object at 0x10860f400>
response = {'content-type': 'text/plain', 'status': '408', 'content-length': 15}
uri = 'http://localhost:58287/'
----------------------------- Captured stderr call -----------------------------
Traceback (most recent call last):
File "/private/tmp/nix-build-python3.8-httplib2-0.19.1.drv-0/source/tests/__init__.py", line 311, in server_socket_thread
fun(client, tick)
File "/private/tmp/nix-build-python3.8-httplib2-0.19.1.drv-0/source/tests/__init__.py", line 392, in server_request_socket_handler
request = HttpRequest.from_buffered(buf)
File "/private/tmp/nix-build-python3.8-httplib2-0.19.1.drv-0/source/tests/__init__.py", line 177, in from_buffered
return parse_http_message(cls, buf)
File "/private/tmp/nix-build-python3.8-httplib2-0.19.1.drv-0/source/tests/__init__.py", line 120, in parse_http_message
start_line = buf.readline()
File "/private/tmp/nix-build-python3.8-httplib2-0.19.1.drv-0/source/tests/__init__.py", line 110, in readline
self._fill(more=1)
File "/private/tmp/nix-build-python3.8-httplib2-0.19.1.drv-0/source/tests/__init__.py", line 81, in _fill
chunk = self._sock.recv(8 << 10)
ConnectionResetError: [Errno 54] Connection reset by peer
```
