Further proposal: Rename my _login_tty to login_tty and make it available as a part of the pty library. Note that usually login_tty accompanies openpty and forkpty on a system; for example, see

https://www.man7.org/linux/man-pages/man3/login_tty.3.html
https://man.openbsd.org/login_tty
https://netbsd.gw.com/cgi-bin/man-cgi?login_tty++NetBSD-current

However, python's pty only offers openpty and forkpty in the form of pty.openpty and pty.fork respectively. While it is true that forkpty [ pty.fork ] combines openpty, fork, and login_tty, it also closes the slave end of the pty, making it unsuitable for situations where the slave end needs to be kept open; for example, in my patch, the slave end is used to set the window size; or, in case someone wants to do even better and register a SIGWINCH handler for situations in which the window size can change.