python > 3.5: Issue with unix domain sockets

[Mark Geisert]

Ken Brown via Cygwin wrote:
> On 5/3/2021 8:57 AM, Maximilian.Blenk--- via Cygwin wrote:
>> Incorrect Behavior:
>> Server:
>> $ python3.7 server.py
>> starting up on ./uds_socket
>> waiting for a connection
>> Traceback (most recent call last):
>>    File "server.py", line 27, in <module>
>>      connection, client_address = sock.accept()
>>    File "/usr/lib/python3.7/socket.py", line 214, in accept
>>      sock = socket(self.family, self.type, self.proto, fileno=fd)
>>    File "/usr/lib/python3.7/socket.py", line 151, in __init__
>>      _socket.socket.__init__(self, family, type, proto, fileno)
>> SystemError: <slot wrapper '__init__' of '_socket.socket' objects> returned NULL 
>> without setting an error
>>
>> Client:
>> $ python3.7 client.py
>> connecting to ./uds_socket
>> sending b'This is the message.  It will be repeated.'
>> closing socket
>> Traceback (most recent call last):
>>    File "client.py", line 27, in <module>
>>      data = sock.recv(16)
>> ConnectionResetError: [Errno 104] Connection reset by peer
> 
> I wonder if this has the same cause as the problem reported here:
> 
>    https://cygwin.com/pipermail/cygwin/2021-February/247884.html
> 
> Mark, can you check that?

Hmm, the correlation between failing Python versions and patch placements is 
troubling.  I've reproduced the OP's findings and will dig further.

..mark