After running a truss I saw this:
stat64("/tmp/tmpin0bBa/var/.migrate/tmp", 0xFD1C8E80) = 0
rename("/tmp/tmpin0bBa/var/pkg/lost+found/var/tmp-20180209T115433Z/A", "/tmp/tmpin0bBa/var/.migrate/tmp/A") Err#1 EPERM
lstat64("/tmp/tmpin0bBa/var/pkg/lost+found/var/tmp-20180209T115433Z/A", 0xFD1C9000) = 0
# cd /var/tmp
# ls -ldV A
-rw-r--r-- 1 andrew staff 0 Mar 11 2013 A
# rm A
rm: A: override protection 644 (yes/no)? yes
rm: A not removed: Not owner
I need to see why i can not delete this file. So it looks nothing to do with Solaris 11.4 beta.
Looks like I played round with file protection in 2013!: Making files on ZFS Immutable (even by root!)
And left it!
# chmod S-ci A
# rm A
Ran the update again and it worked like a dream. Will not switch yet, since I need to get the graphics card to work with this version, but that is a different story.