kernel crash from adjacent partitions (gpart, zfs)

[Peter]

Hi,

  when creating partitions directly adjacent without a safety free space 
between them, the kernel may crash.

Does anybody know how big that free space needs to be?

How I found out (and how to reproduce the crash):
https://forums.freebsd.org/threads/create-degraded-raid-5-with-2-disks-on-freebsd.70750/post-426756

OS concerned: 11.2, amd64 and i386.

Or, does anybody know if this is fixed in 12?