Here's a simple summary of the problem:
    : jrbarnette $REPOS/cros.base/chromeos-admin; git grep -l 'atest stable_version' 
    lab-tools/create_beaglebone_images
    lab-tools/update_servohost
    lab-tools/validate_deployment
    venv/server_management_lib/tasks/atomic_shard.py
    venv/server_management_lib/tasks/staging_lab_task.py

Every listed file is a likely source of an obsolete, no longer
working command invocation.

The following revision refers to this bug:
  https://chrome-internal.googlesource.com/chromeos/chromeos-admin/+/28fc3576165db91390adc57eb6db34f8c1b3eb49

commit 28fc3576165db91390adc57eb6db34f8c1b3eb49
Author: Richard Barnette <jrbarnette@google.com>
Date: Tue May 01 22:46:13 2018

The tools we use regularly are fixed:
    lab-tools/create_beaglebone_images
    lab-tools/update_servohost
    lab-tools/validate_deployment

However, some server-management library code also still depends on
`atest stable_version`.  That code appears to be dead, meaning most
likely the code should be deleted.

However, there's some possibility that rather than merely deleting
the code, work should be done to put the code (or at least, the
intended feature) into service.  What that means is TBD.

The following revision refers to this bug:
  https://chrome-internal.googlesource.com/chromeos/chromeos-admin/+/c2496a1de742a413bed92b079e213ae7e9846628

commit c2496a1de742a413bed92b079e213ae7e9846628
Author: Richard Barnette <jrbarnette@google.com>
Date: Thu Jun 14 14:45:25 2018

I'm declaring victory here.  The SML code in chromeos-admin
that I changed really should have been deleted rather than
just changed, but making that so exceeds my ration of time
and patience.

So, we'll just leave the dead code not obviously broken.  :-(