double check for mounted overlay-root filesystems before umount
Created by: philmmanjaro
In some rare cases you might start with a dirty system:
==> Cleaning up ...
-> Deleting chroot 'kde-image'...
-> Deleting chroot 'root-image'...
rm: cannot remove '/var/lib/manjaro-tools/buildiso/kde-minimal/x86_64/root-image': Device or resource busy
rm: cannot remove '/var/lib/manjaro-tools/buildiso/kde-minimal/x86_64/root-image': Device or resource busy
we should find a way to detect and prevent it ...