Here is the sample failure message,

failed cbuildbot_launch [veyron_fievel-release] failed DebugSymbols failed Report

 PATH: /b/cipd_client:/b/cipd_path_tools:/b/cipd_path_tools/bin:/b/rr/tmpeKkD3M/w/depot_tools:/b/cipd_path_tools:/b/cipd_path_tools/bin:/b/cipd_client:/home/chrome-bot/slavebin:/b/depot_tools:/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin
 PWD: /b/build/slave/veyron_fievel-release-release-R66-10452.B/build
 PYTHONIOENCODING: UTF-8
 PYTHONPATH: /b/build/site_config:/b/build/scripts:/b/build/scripts/release:/b/build/third_party:/b/build/third_party/google_api_python_client:/b/build/third_party/httplib2/python2:/b/build/third_party/infra_libs:/b/build/third_party/oauth2client:/b/build/third_party/pyasn1:/b/build/third_party/pyasn1-modules:/b/build/third_party/python-rsa:/b/build/third_party/requests_2_10_0:/b/build/third_party/setuptools-0.6c11:/b/build/third_party/site-packages:/b/build/third_party/uritemplate:/b/build_internal/site_config:/b/build_internal/symsrc:/b/build/slave:/b/build/third_party/buildbot_slave_8_4:/b/build/third_party/twisted_10_2:
 PYTHONUNBUFFERED: 1
 TESTING_SLAVENAME: cros-beefy328-c2
 USER: chrome-bot
 USERNAME: chrome-bot
 VPYTHON_CLEAR_PYTHONPATH: 1
 VPYTHON_VIRTUALENV_ROOT: /b/c/vpython
20:21:41: INFO: Starting new HTTP connection (1): metadata.google.internal
20:21:41: DEBUG: "GET /computeMetadata/v1/instance/zone HTTP/1.1" 200 41
step returned non-zero exit code: 1

https://luci-milo.appspot.com/buildbot/chromeos_release/veyron_fievel-release%20release-R66-10452.B/56