ob_is_tty returns false for stdin even when stdin is a tty

[hartmans]

ob_is_tty calls get_fileno and then does

if fileno:

The problem is that stdin has fileno 0, and 0 is falsy, so this is always false for stdin.
So, similar to what's going on in #414 , you will never be able to pass an unmodified stdin tty through to the subprocess.
Probably that should be

if fileno is None:

[amoffat]

I think you mean fileno is not None, but yes, excellent catch on this 👍 . 1e15190 will go out with the next release