Thank you for checking. If this issue happens even when Python is run manually from an ordinary shell, fixing it in the same way as in #30225 is probably not what you want because while the error message will be gone the corresponding std stream will be None (sys.stdin in the case that you ktrace'd). However, if fd 0 really becomes unusable for some reason, there isn't anything Python can do.

Given your description and ktrace log, I can't imagine why fd 0 would behave strangely only in Python. I've attached a small C program to check fd 0. Could you compile it and run in an infinite loop from the shell in an attempt to reproduce this?