Fix port selection bug

[AlphonsG]

Old conditional would not result in port 0 being selected if specified by the user.

[AlphonsG]

For: #9

[Dragon2fly]

Hi @AlphonsG

Please add the test for your pull request.
You can refer to this previous test , set the port to 0 and try out.

[AlphonsG]

Hello @Dragon2fly , I tried writing a test based on the one you linked, but it was failing due to the way the logging is implemented. For example, if we have port 0 assign an unused port to the logger, then if you reinitialise that logger in a spawned process (specifying port 0 again), then you won't log to the same address as the logger in the parent process. I tried passing the parent logger to the child as an argument, but nothing was logged in the child process. It seems the "fix" would need to be a bit more involved than I'd initially thought.

For anyone wanting to assign an unused port to logger_tt, I suggest they just determine the port number first and then pass that to logger_tt, for example:

with socket.socket() as s:
    s.bind(('', 0))  # bind to a free port
    port = s.getsockname()[1]

then pass the port to setup_logging.

Perhaps it can be added to the documentation then that assigning port 0 to logger_tt actually assigns port handlers.DEFAULT_TCP_LOGGING_PORT?

Thanks for requesting a test for this by the way, it would've caused issues if merged.