Yes, thanks for the report, i forgot to change this message, it will be fixed on the next release.
Humm, try to do the same thing (when a trouble occur about the mounting point) with system:D as init without ISO rescue.... good luck :D. In those case, we see the advantage to have an earlier tty to debug the things :)
Note : /run/boot/uncaught-logs/current to see the log of the boot process. from the s6-boot wiki page :
https://wiki.obarun.org/doku.php?id=s6-boot
If something go wrong at boot time, you can able to see what's happened viewing the file /run/boot/uncaught-logs/current.
The log output is written with a TAI64N timestamp format e.g :
# cat /run/boot/uncaught-logs/current
@ 4000000059db0f3d2a0aa454 00 started
@ 4000000059db0f3d2a1402c4 Mounting filesystem