https://luci-milo.appspot.com/buildbot/chromeos/pyro-release/1227
[Test-Logs]: dummy_PassServer.sanity_SERVER_JOB: FAIL

Looking at child job:
http://cautotest-prod.corp.google.com/afe/#tab_id=view_job&object_id=158822266

https://pantheon.corp.google.com/storage/browser/chromeos-autotest-results/158822266-chromeos-test/chromeos2-row4-rack4-host4/ssp_logs/debug/

11/26 12:47:37.079 INFO |        server_job:0213| FAIL	----	----	timestamp=1511729257	localtime=Nov 26 12:47:37	Failed to setup container for test: Command <sudo lxc-start -P /usr/local/autotest/containers -n test_158822266_1511728954_27280 -d> failed, rc=1, Command returned non-zero exit status
  * Command: 
      sudo lxc-start -P /usr/local/autotest/containers -n
      test_158822266_1511728954_27280 -d
  Exit status: 1
  Duration: 6.08941507339
  
  stderr:
  lxc-start: tools/lxc_start.c: main: 366 The container failed to start.
  lxc-start: tools/lxc_start.c: main: 368 To get more details, run the container in foreground mode.
  lxc-start: tools/lxc_start.c: main: 370 Additional information can be obtained by setting the --logfile and --logpriority options.. Check logs in ssp_logs folder for more details.

This looks a lot like https://bugs.chromium.org/p/chromium/issues/detail?id=788455 to me.