This is reportedly a problem with some emulated PS/2 controllers.
glauxosdever reported his computer responds 0x50 0x00 instead of just 0x00.
OpenBSD has commented out this check in sys/dev/ic/pckbc.c, claiming it's a
problem with some controllers and that some might even hang.
I doubt not testing ports is going to be a problem, as the identitication
code runs next and verifies devices and all relevant modern hardware
probably has this working well enough.
Jonas 'Sortie' Termansen