On windows, s=input() is cleanly interrupted by ^-C, leaving s unbound, before and after the patch.  time.sleep(1) is not interrupted, before and after the patch.  Ditto for the socket test.  Louie, what test are you using on *nix?

It still appears that for Windows a patch to signalmodule.c is still needed.  Eryk and Nathaniel, can you agree on an actual patch?

Eryk: off topic a bit, but
>>> open('con', 'w').write('spam\n')
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    open('con', 'w').write('spam\n')
OSError: [WinError 6] The handle is invalid: 'con'