The code that initializes ostree repo does not work correctly. It only runs ostree init if the target directory (/mnt/koji/compose/atomic/rawhide etc.) does not exist.

But if it does not exist, the runroot task will fail because it will not be able to mount it.

If the target dir is manually created, pungi-make-ostree will fail because the repo was not initialized.

We need to change the check to run init if the target dir exists but is empty.