When restoring the backup the rootfs is mounted in /rootfs/data
and the symlink to the real file would then not work. Attempt to
change the directory first to get a relative symlink.
Untested change and needed for rauc
With the ro image we have a cheap way to figure out which
files were changed. We can run cmp between the to be backed
up file. This way the stored data will be minimal in the
sense of changed files.
Holger Hans Peter Freyther