Running test_that for a servo test (e.g. platform_ServoPowerStateController),
you find messages like this:
    06/15 13:21:14.169 INFO |        servo_host:0599| Applying an update to the servo host, if necessary.
    06/15 13:21:14.169 DEBUG|          ssh_host:0180| Running (ssh) 'grep -q CHROMEO
S /etc/lsb-release'
[ ... ]
    06/15 13:21:14.800 INFO |        servo_host:0536| Using devserver url: http://100.107.160.1:8082/update/beaglebone_servo-release/R53-8368.0.0 to trigger update on servo host 100.96.51.85, from 8316.0.0 to 8368.0.0

There's nothing in the servo update check to block this attempt
for a servo V3 when the test is invoked from test_that.

We shouldn't check for an update when called from test_that,
_even if the servo is actually in the lab_.  We especially shouldn't
check for update from test_that if the servo V3 is on a desktop.