This is inline with the OCI runtime spec:
On POSIX platforms, path is either an absolute path or a relative path
to the bundle. For example, with a bundle at /to/bundle and a root
filesystem at /to/bundle/rootfs, the path value can be either
/to/bundle/rootfs or rootfs. The value SHOULD be the conventional
rootfs.
(https://github.com/opencontainers/runtime-spec/blob/master/config.md)