Post-install black run can fail on MacOS due to AF_UNIX path length limitation

[charles-dyfis-net]

@nix { "action": "setPhase", "phase": "installCheckPhase" }
running install tests
Running black ...
src/pypi2nix.egg-info ignored: matches the .gitignore file content
Process SyncManager-1:
Traceback (most recent call last):
  File "/nix/store/81qani7sdir46gjwf3a3jr2cv1aggkz1-python3-3.7.5/lib/python3.7/multiprocessing/process.py", line 297, in _bootstrap
    self.run()
  File "/nix/store/81qani7sdir46gjwf3a3jr2cv1aggkz1-python3-3.7.5/lib/python3.7/multiprocessing/process.py", line 99, in run
    self._target(*self._args, **self._kwargs)
  File "/nix/store/81qani7sdir46gjwf3a3jr2cv1aggkz1-python3-3.7.5/lib/python3.7/multiprocessing/managers.py", line 589, in _run_server
    server = cls._Server(registry, address, authkey, serializer)
  File "/nix/store/81qani7sdir46gjwf3a3jr2cv1aggkz1-python3-3.7.5/lib/python3.7/multiprocessing/managers.py", line 145, in __init__
    self.listener = Listener(address=address, backlog=16)
  File "/nix/store/81qani7sdir46gjwf3a3jr2cv1aggkz1-python3-3.7.5/lib/python3.7/multiprocessing/connection.py", line 438, in __init__
    self._listener = SocketListener(address, family, backlog)
  File "/nix/store/81qani7sdir46gjwf3a3jr2cv1aggkz1-python3-3.7.5/lib/python3.7/multiprocessing/connection.py", line 581, in __init__
    self._socket.bind(address)
OSError: AF_UNIX path too long

Appears to be the same issue previously observed as NixOS/nixos#77 and fixed by disabling tests on MacOS in NixOS/nixpkgs@ed87cc2e4e8abc346262a268bb0999565ae89c41

[seppeljordan]

Hi, macOS is not supported. If someone would want to maintain this package for macOS, this could could change.