Cleanup extra boolean (used by spa not zvol)
merge restore - Enforce strict validation for aux vdevs
Comparing to illumOS, ZoL, and FreeBSD, this is set to strict validation for auxiliary vdevs, on vdev_reopen.
It appears this change happened in 295304bed6fa6744b8d011e36b9c2180311cedb2, and the other change to vdev.c is already applied here. Suspect an evil merge in the past.