This happens between the update_scripts step and LogDog bootstrap step (No logdog link because logdog hasn't been bootstrapped yet)

https://build.chromium.org/p/tryserver.webrtc/builders/win_rel/builds/28150/steps/steps/logs/stdio

===
INFO:remote_run:Executing command: ['E:\\b\\depot_tools\\win_tools-2_7_6_bin\\python\\bin\\python.exe', '../../../scripts/slave/remote_run.py', '--repository', 'https://chromium.googlesource.com/chromium/tools/build.git', '--revision', 'refs/heads/master', '--recipe', 'webrtc/standalone', '--build-properties-gz=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', '--factory-properties-gz=eNo9jEEOwyAMBP/icwV3PoOI44AVwAgbVVXVv5dTbquZ0X5hJCsRpV+cIcDNhoU6vGAS8qCN3nRMQ6+W+pmqdHpknDRE2WR+dlfMhgbvsUxpvJrLIrmSyppIDqU9xptIVX8srqfLbPtwKcW9ePcQrlSVfn9ACTlb']
INFO:remote_run:Using temporary directory: 'E:\\b\\rr\\tmpg1btcf'.
INFO:remote_run:Using build data directory: 'E:\\b\\rr\\tmphmtucg'.
INFO:remote_run:Using properties: {u'workdir': u'E:\\b\\build\\slave/win', 'builder_id': u'master.tryserver.webrtc:win_rel', u'repository': u'', u'buildername': u'win_rel', u'recipe': u'webrtc/standalone', u'mastername': u'tryserver.webrtc', u'patch_storage': u'rietveld', u'buildbucket': u'{"build": {"bucket": "master.tryserver.webrtc", "created_by": "user:ehmaldonado@webrtc.org", "created_ts": "1501142190078750", "id": "8972932042854164336", "lease_key": "843610147", "tags": ["builder:win_rel", "buildset:patch/rietveld/codereview.webrtc.org/2982123002/1", "master:tryserver.webrtc", "user_agent:rietveld"]}}', u'requester': u'ehmaldonado@webrtc.org', u'buildbotURL': u'http://build.chromium.org/p/tryserver.webrtc/', u'patch_project': u'webrtc', u'buildnumber': 28150, u'rietveld': u'https://codereview.webrtc.org', 'build_data_dir': 'E:\\b\\rr\\tmphmtucg', u'issue': 2982123002L, u'recipe_repository': u'https://chromium.googlesource.com/chromium/tools/build.git', u'project': u'', u'slavename': u'vm212-m4', u'blamelist': [u'ehmaldonado@webrtc.org'], u'branch': u'', u'master': u'tryserver.webrtc', u'patchset': 1, u'use_gitiles': False, u'requestedAt': 1501142202, u'revision': u''}
INFO:monitoring_utils:Executing command: ['C:\\infra-python\\ENV\\Scripts\\python.exe', 'C:\\infra-python\\run.py', 'infra.tools.send_monitoring_event', '--event-mon-output-file', 'E:\\b\\rr\\tmphmtucg\\log_request_proto', '--event-mon-run-type', 'file', '--event-mon-service-name', u'buildbot/master/master.tryserver.webrtc', '--build-event-build-name', u'win_rel', '--build-event-build-number', '28150', '--build-event-build-scheduling-time', '1501142202000', '--build-event-type', 'BUILD', '--event-mon-timestamp-kind', 'POINT', '--build-event-hostname', 'VM212-M4']
Traceback (most recent call last):
  File "C:\infra-python\ENV\lib\site.py", line 711, in <module>
    main()
  File "C:\infra-python\ENV\lib\site.py", line 700, in main
    aliasmbcs()
  File "C:\infra-python\ENV\lib\site.py", line 515, in aliasmbcs
    import locale, codecs
  File "C:\infra-python\ENV\lib\locale.py", line 19, in <module>
    import functools
ImportError: No module named functools
WARNING:monitoring_utils:Failed to send monitoring event.
Traceback (most recent call last):
  File "E:\b\build\scripts\slave\monitoring_utils.py", line 81, in write_build_monitoring_event
    _check_call(cmd)
  File "E:\b\build\scripts\slave\monitoring_utils.py", line 38, in _check_call
    subprocess.check_call(cmd, **kwargs)
  File "E:\b\depot_tools\win_tools-2_7_6_bin\python\bin\lib\subprocess.py", line 540, in check_call
    raise CalledProcessError(retcode, cmd)
CalledProcessError: Command '['C:\\infra-python\\ENV\\Scripts\\python.exe', 'C:\\infra-python\\run.py', 'infra.tools.send_monitoring_event', '--event-mon-output-file', 'E:\\b\\rr\\tmphmtucg\\log_request_proto', '--event-mon-run-type', 'file', '--event-mon-service-name', u'buildbot/master/master.tryserver.webrtc', '--build-event-build-name', u'win_rel', '--build-event-build-number', '28150', '--build-event-build-scheduling-time', '1501142202000', '--build-event-type', 'BUILD', '--event-mon-timestamp-kind', 'POINT', '--build-event-hostname', 'VM212-M4']' returned non-zero exit status 1
INFO:slave.cipd_bootstrap_v2:bootstrapping CIPD
INFO:slave.cipd_bootstrap_v2:using staging revision
INFO:slave.cipd_bootstrap_v2:ensuring cipd client E:\b\cipd_client\cipd.exe @ git_revision:5cf65fdf804a9b3f3023f79d5b3cab2a88ccd09e
INFO:slave.cipd_bootstrap_v2:Running ['E:\\b\\cipd_client\\cipd.exe', 'selfupdate', '-version', 'git_revision:5cf65fdf804a9b3f3023f79d5b3cab2a88ccd09e']
INFO:slave.cipd_bootstrap_v2:Executing CIPD command: ['cipd.exe', 'ensure', '-ensure-file', '-', '-root', 'E:\\b\\cipd_path_tools']
Manifest:
infra/tools/luci/vpython/${platform} git_revision:5cf65fdf804a9b3f3023f79d5b3cab2a88ccd09e
infra/tools/git/${platform} git_revision:5cf65fdf804a9b3f3023f79d5b3cab2a88ccd09e
infra/python/cpython/${os=windows}-${arch=386,amd64} version:2.7.13.chromium7
infra/git/${os}-${arch=386,amd64} version:2.13.3.chromium10
INFO:slave.cipd_bootstrap_v2:Executing CIPD command: ['cipd.exe', 'ensure', '-ensure-file', '-', '-root', 'E:\\b\\.remote_run_cipd']
Manifest:
infra/tools/luci/kitchen/${platform} git_revision:626f893e5822aa2fbea113c0c2e023f2a601c463
===

This doesn't fail the build, but we aren't getting ts_mon metrics out of this build.