since commit 139acf37 ("tape: inventory: skip unassigned tapes")
we skip unassigned tapes (special all-zero media-set uuid) when we look
for a catalog. We accidentally skipped storing it in the inventory
completely, which means we never inventoried completely empty tapes.
to fix that, simply move the check below the inserting in the inventory
Fixes: 139acf37 ("tape: inventory: skip unassigned tapes")
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>