Comment # 4 on bug 1208725 from Michal Suchanek

SDL does

kbd->console_fd = open("/dev/tty", O_RDONLY | O_CLOEXEC);
ioctl(kbd->console_fd, KDSKBMODE, K_OFF);

but that's different device from /dev/tty0

And 

kbd_mode -fu /dev/tty0 

seems to undo it.