Message 239280 - Python tracker

> I'm going to be honest; seeing None being returned from a pipe read feels *really* broken to me. When I get None returned from an IO read operation, my first instinct is "there can't be anything else coming, why else would it return None?"

It is how it is done in similar cases (returning `None` to indicate 
"would block"). Do you know a better method that would allow to 
distinguish between EOF (no future data, ever) and "would block"
(future data possible) without calling process.poll()?