> Also, what is the rationale for the following change:
> 
> -            elif timeout == 0.0:
> +            elif timeout == 0.0 and nleft != 0:
>                  return False

If PeekNamedPipe() returns (navail, nleft) there are 3 cases:

1) navail > 0: just return True
2) navail = nleft = 0: either pipe is empty or next message is empty
   so fall through to slow path to find out which.
3) navail = 0, nleft > 0: a non-empty message is coming, but nothing 
   is available yet.

The check is a shortcut for case 3, although it probably never 
occurs.  I've removed that check in the new patch, and added the 
unit tests to test_multiprocessing.

> There is infrastructure in _multiprocessing to handle Ctrl-C. Look 
> for "sigint_event" in Modules/_multiprocessing/*. This could be 
> the topic of a separate issue and patch.

I will look in to it.