Chromedriver Win7 bot is failing since yesterday night.

https://build.chromium.org/p/chromium.chromedriver/builders/Win7/builds/17165

Traceback (most recent call last):
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\run.py", line 413, in run
    recipe_result = recipe_script.run(api, api._engine.properties)
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\loader.py", line 57, in run
    self.RunSteps, properties, self.PROPERTIES, api=api)
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\loader.py", line 521, in invoke_with_properties
    **additional_args)
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\loader.py", line 482, in _invoke_with_properties
    return callable_obj(*props, **additional_args)
  File "E:\b\build\scripts/slave\recipes\chromium.chromedriver.recipe_autogen.py", line 281, in RunSteps
    dispatch_directory[api.properties["buildername"]](api)
  File "E:\b\build\scripts/slave\recipes\chromium.chromedriver.recipe_autogen.py", line 180, in Win7_steps
    result = api.bot_update.ensure_checkout(force=True)
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\recipe_api.py", line 239, in _inner
    return func(*a, **kw)
  File "E:\b\build\scripts\slave\.recipe_deps\depot_tools\recipe_modules\bot_update\api.py", line 286, in ensure_checkout
    co_root = step_result.json.output['root']
KeyError: 'root'

Could someone please take a look?

Thanks.