Pungi can use either genisoimage or xorriso to create ISOs.
It also needed isoinfo utility for querying volume ID from the ISO
image. However, the utility is part of the genisoimage suite of tools.
On systems that no longer provide genisoimage, the image would be
successfully generate with xorriso, but then pungi would fail to extract
the volume id leading to metadata with missing values.
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>