This hints at a race condition.

I *think* that the problem is that at the time the ‘console-font-X’
service starts and invokes ‘unicode_start’, it may be that mingetty
hasn’t opened the tty yet.

Indeed, the ‘term-ttyX’ services are considered started as soon as
mingetty is running, but there’s a chance that it’s running and has not
opened the tty yet.

I think we should use another implementation that doesn’t have this
problem (agetty?).  Given that mingetty.c is 400 lines, we might as well
do it in Scheme.

Ludo’.