qmrestore doesn't catch an error during restore when source "storage" is disalbed:
$ qmrestore /mnt/pve/backup-stop/vzdump-qemu-103-2010_09_18-04_27_47.tgz 118
INFO: restore QemuServer backup '/mnt/pve/backup-stop/vzdump-qemu-103-2010_09_18-04_27_47.tgz' using ID 118
INFO: extracting...