Attached patch changes time.sleep() to retry select() when select() is interrupted by a signal or retry WaitForSingleObjectEx() when the signal SIGINT is received on Windows.

The patch drops support for EMX, sorry! I didn't know EMX, I had to Google it: "EMX is a free 32-bit DOS extender which adds some properties of Unix to MS-compatible DOS and IBM's OS/2 operating systems." (OS/2 support was dropped in Python 3.4  by the PEP 11.)

The patch also drops support for Watcom C compiler. I guess that it's also something specific to MS-DOS or very old (and unsupported) Windows versions.

select.select() is available on all platforms according to the doc, so I don't understand why we would not use it on all platforms for time.sleep() in 2015!
https://docs.python.org/dev/library/select.html#select.select