If .bootloader_revision is missing, create one

[by]

Upon first run on the next machine, rpi-update (next) threw the error cat:/boot/firmware/.bootloader_revision: No such file or directory

After touch /boot/firmware/.bootloader_revision , the error was gone, so it would be good if rpi-update creates a new (empty) file if none is existing, yet.

I assume the same might be true for .firmware_revision ?

Thanks you!