[on-discuss] heads-up: build 102 toxic for zfs root users

[eric taylor]

If you have a system with a zfs root running build 102, the fix
for:

     6752810 deadlock when trying to online missing boot drive

introduced a bug which can cause panics and/or data corruption
involving the root pool.  This typically will happen when the
system is doing I/O when being shut down.(e.g. luactivate followed
by init 6), but can happen in other situations as well.

This change has been backed out of build 103 and the BFU archives
as of 11/15 and later.

-  Eric