Prior to pushing a new servo V3 build to the lab, we run through
a testing procedure describe here:
    https://sites.google.com/a/google.com/chromeos/for-team-members/infrastructure/chromeos-admin/update-beaglebone-servo

That procedure has two notable problems:
 1) The procedure requires a local servo V3 on your desktop.
 2) The procedure tests servod sanity, but doesn't check AU
    sanity.

To date, the procedure has been adequate to the task, but we
should do better.  The lab tools already have a script called
update_beaglebone.  We should augment or replace the documented
test procedure with the following steps:
  * Select a DUT with a servo from the lab
  * Lock the DUT.
  * Run update_beaglebone to get to the target version.
  * Run a servo sanity check of some sort (maybe just servo-stat).
  * Run update_beaglebone to revert the target servo V3.
  * Unlock the target DUT.

Better still, we could write a script to perform most of the steps
automatically (DUT selection is likely easier as a manual procedure).