https://build.chromium.org/p/chromium.perf/builders/Win%207%20Nvidia%20GPU%20Perf/builds/1113


Log:
[  FAILED  ] sequence-conversion-custom-iterator.html (4824 ms)
c:\b\s\w\ir\third_party\catapult\telemetry\telemetry\internal\image_processing\_bitmap.py:152: UserWarning: Using pure python png decoder, which could be very slow. To speed up, consider installing numpy & cv2 (OpenCV).
  'Using pure python png decoder, which could be very slow. To speed up, '
(INFO) 2017-08-10 10:01:58,720 browser.Close:268  Closing browser (pid=3508) ...
(INFO) 2017-08-10 10:01:59,026 desktop_browser_backend._TryCooperativeShutdown:618  Successfully shut down browser cooperatively
(INFO) 2017-08-10 10:01:59,030 browser.Close:283  Browser is closed.
(INFO) 2017-08-10 10:01:59,914 exception_formatter.PrintFormattedException:19  Try printing formatted exception: None None None
Traceback (most recent call last):
  RunBenchmark at c:\b\s\w\ir\third_party\catapult\telemetry\telemetry\internal\story_runner.py:340
    expectations=expectations, metadata=benchmark.GetMetadata())
  Run at c:\b\s\w\ir\third_party\catapult\telemetry\telemetry\internal\story_runner.py:203
    _RunStoryAndProcessErrorIfNeeded(story, results, state, test)
  _RunStoryAndProcessErrorIfNeeded at c:\b\s\w\ir\third_party\catapult\telemetry\telemetry\internal\story_runner.py:105
    state.RunStory(results)
  traced_function at c:\b\s\w\ir\third_party\catapult\common\py_trace_event\py_trace_event\trace_event_impl\decorators.py:52
    return func(*args, **kwargs)
  RunStory at c:\b\s\w\ir\third_party\catapult\telemetry\telemetry\page\shared_page_state.py:319
    self._current_page, self._current_tab, results)
  traced_function at c:\b\s\w\ir\third_party\catapult\common\py_trace_event\py_trace_event\trace_event_impl\decorators.py:52
    return func(*args, **kwargs)
  ValidateAndMeasurePage at c:\b\s\w\ir\tools\perf\benchmarks\blink_perf.py:326
    results.current_page, metric, units, values))
  __init__ at c:\b\s\w\ir\third_party\catapult\telemetry\telemetry\value\list_of_scalar_values.py:83
    assert len(values) > 0
AssertionError
Locals:
  description           : None
  grouping_keys         : None
  important             : True
  improvement_direction : None
  name                  : 'sequence-conversion-custom-iterator'
  none_value_reason     : None
  page                  : <telemetry.page.Page object at 0x038F61B0>
  std                   : None
  tir_label             : None
  units                 : u'runs/s'
  values                : []

Typically, this shouldn't be a red step as it is a run of a reference build benchmark. I suspect it has to do with the exception being uncaught by core Telemetry, hence it caused invalid test result --> red step.

I will make fix for this in blink_perf & see if this fixes it.