There're some errors in starting devservers on DUT:
https://pantheon.corp.google.com/storage/browser/chromeos-autotest-results/79092978-chromeos-test/chromeos4-row12-rack6-host5/sysinfo/
https://pantheon.corp.google.com/storage/browser/chromeos-autotest-results/79101667-chromeos-test/chromeos4-row12-rack6-host5/sysinfo/


2016/10/03 06:50:11.922 DEBUG|    cros_build_lib:0565| RunCommand: ssh -p 22 '-oConnectionAttempts=4' '-oUserKnownHostsFile=/dev/null' '-oProtocol=2' '-oConnectTimeout=30' '-oServerAliveCountMax=3' '-oStrictHostKeyChecking=no' '-oServerAliveInterval=10' '-oNumberOfPasswordPrompts=0' '-oIdentitiesOnly=yes' -i /tmp/ssh-tmpP5Km1P/testing_rsa root@chromeos4-row12-rack6-host5 -- python /mnt/stateful_partition/unencrypted/preserve/cros-update/tmp.8NEQNgNMo3/src/devserver.py --help
Warning: Permanently added 'chromeos4-row12-rack6-host5,100.115.203.9' (RSA) to the list of known hosts.
Traceback (most recent call last):
  File "/mnt/stateful_partition/unencrypted/preserve/cros-update/tmp.8NEQNgNMo3/src/devserver.py", line 64, in <module>
    import autoupdate
  File "/mnt/stateful_partition/unencrypted/preserve/cros-update/tmp.8NEQNgNMo3/src/autoupdate.py", line 34, in <module>
    import update_payload
  File "/mnt/stateful_partition/unencrypted/preserve/cros-update/tmp.8NEQNgNMo3/src/host/lib/update_payload/__init__.py", line 9, in <module>
    from checker import CHECKS_TO_DISABLE
  File "/mnt/stateful_partition/unencrypted/preserve/cros-update/tmp.8NEQNgNMo3/src/host/lib/update_payload/checker.py", line 24, in <module>
    import common
  File "/mnt/stateful_partition/unencrypted/preserve/cros-update/tmp.8NEQNgNMo3/src/host/lib/update_payload/common.py", line 10, in <module>
    import update_metadata_pb2
  File "/mnt/stateful_partition/unencrypted/preserve/cros-update/tmp.8NEQNgNMo3/src/host/lib/update_payload/update_metadata_pb2.py", line 561, in <module>
    DESCRIPTOR.message_types_by_name['Extent'] = _EXTENT
AttributeError: 'FileDescriptor' object has no attribute 'message_types_by_name'
2016/10/03 06:50:12.337 WARNI|      auto_updater:0245| Cannot start devserver: return code: 1; command: ssh -p 22 '-oConnectionAttempts=4' '-oUserKnownHostsFile=/dev/null' '-oProtocol=2' '-oConnectTimeout=30' '-oServerAliveCountMax=3' '-oStrictHostKeyChecking=no' '-oServerAliveInterval=10' '-oNumberOfPasswordPrompts=0' '-oIdentitiesOnly=yes' -i /tmp/ssh-tmpP5Km1P/testing_rsa root@chromeos4-row12-rack6-host5 -- python /mnt/stateful_partition/unencrypted/preserve/cros-update/tmp.8NEQNgNMo3/src/devserver.py --help
cwd=None, extra env={'LC_MESSAGES': 'C'}

Not sure why this happens on this particular DUT.