> > Why changing PyFile_FromFd() and not io.open() directly?
>
> I must admit I'm a bit lazy, and changing io.open() means changing 
> a fundamental public API, as Guido said on python-dev, so 
> more discussion and some parts of the patches delayed to 3.1.

You're right, and PyFile_FromFd() is also a fundamental "public" API. 
Since TextIOWrapper doesn't support real unbuffered buffer (only 
pseudo line buffer: unbuffered raw buffer and line buffering for 
TextIOWrapper), I prefer to change only stdout/stderr instead of 
PyFile_FromFd(). 

My new patch only changes initstdio() using pitrou's code.

Should we also change stdin?