Force root/root as names for uid0/gid0 instead of using the system
names. This helps make packed download tarballs more reproducible
Signed-off-by: Felix Fietkau <nbd@nbd.name>
The "tar" utility is required to bootstrap XZ which is required to handle
.tar.xz archives, therfore revert to using the bz2 archive.
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
