Finding the git hash for a build

I need to roll back my system to main-n271000-5654b42142e1. After an update
of the system today, it crashes in network startup and I need to get back
to a working system while I try to figure out why it won't boot. Probably
by bisecting the source.

Right now, I am getting an error from 'geli attach' of:
geli: Invalid class name 'eli'.
This is probably the result of kernel and world not being in sync as I had
to restore the boot/modules directory to the state of the old kernel.

I had assumed that the version was a hash that I could use to get my kernel
and world back to a working state. I could restore from backup, but would
like to get back to the exact system of the kernel.old.

I am just a git newby and trying to use 5654b42142e1 reports that the hash
is not found. I'lladmit that I'm lost!
-- 
Kevin Oberman, Part time kid herder and retired Network Engineer
E-mail: rkoberman@gmail.com
PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683