When mount -t lustre ... has failed to actually mount a target, the exit code of mount does not reflect this:

# mount -t lustre zfs_pool_scsi0QEMU_QEMU_HARDDISK_disk13/MGS /mnt/MGS
e2label: No such file or directory while trying to open zfs_pool_scsi0QEMU_QEMU_HARDDISK_disk13/MGS
Couldn't find valid filesystem superblock.
# echo $?
0

This of course wreaks havoc on systems such as IML which rely on the exit code of one step in the process of starting a filesystem to decide if it should continue with subsequent steps.