DF-2584 control — STOCK kernel, PRISTINE image (uncrafted), same sequence
$ sh /root/run2584.sh /root/h2pristine.img
MOUNT-OK
-rw-r--r--  1 root  wheel  32768 Oct 14 09:14 /mnt/h2/f
stat: inum=1024 size=32768
1+0 records in / 1+0 records out / 32768 bytes transferred
SYNC-SURVIVED (no panic)
UMOUNT-OK
=> identical build/mount/write/sync on the uncrafted image: no crash.