Handshake error when connecting via ws+unix

[litteratum]

I have a WebSocket service that uses the gevent-websocket library. And ws4py connects to it via a Unix socket without issue.

Recently, I switched to flask-sock (uses simple-websocket under the hood) for the server.
And now handshake fails.

With trial and error (andd LLMs help), I discovered that a workaround is to set ws.port explicitly.
So, how I do it:

from ws4py.client.geventclient import WebSocketClient

_URL = "ws+unix:///tmp/sock.sock"

ws = WebSocketClient(_URL)

if ws.port is None:
    if ws.scheme == "wss":
        ws.port = 443
    else:
        ws.port = 80

ws.connect()

When the port is set, the handshake is now successful. Also, the port value is not important; even when set to "0", it works.

I see that the library always set the host (localhost in this case). Shouldn't the library also set the port?