LGTM on Windows 7:

    Python 3.5.0b4+ (default, Jul 27 2015, 17:46:34) [MSC v.1900 64 bit (AMD64)] on win32
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import socket
    >>> sock = socket.socket()
    >>> sock.bind(('127.0.0.1', 52380))
    >>> sock.listen(5)
    >>> sock.setblocking(False)
    >>> csock, addr = sock.accept()
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "C:\Source\cpython\3.5\lib\socket.py", line 195, in accept
        fd, addr = self._accept()
    BlockingIOError: [WinError 10035] A non-blocking socket operation could not be completed immediately