At comment:2:ticket:24642, we were surprised to find that server transports get `TOR_PT_EXIT_ON_STDIN_CLOSE=1` set, and client transports do not. https://gitweb.torproject.org/tor.git/tree/src/or/transports.c?id=9e8b762fcecfece64aae70ae640aaa59fd227ca5#n1387 We expected that it would be set for both. Client PTs have code to deal with `TOR_PT_EXIT_ON_STDIN_CLOSE`, which it turns out has been going unused.