"""
6572 2018-10-31 17:59:35.473 E: internal failure: 'e98c19a51e39462ccff52ca52af6dd40e68b6546'
Traceback (most recent call last):
  File "C:\b\s\swarming_bot.1.zip\client\run_isolated.py", line 721, in map_and_run
    with data.install_packages_fn(run_dir) as cipd_info:
  File "C:\tools\python\bin\lib\contextlib.py", line 17, in __enter__
    return self.gen.next()
  File "C:\b\s\swarming_bot.1.zip\client\run_isolated.py", line 1030, in install_client_and_packages
    with client_manager as client:
  File "C:\tools\python\bin\lib\contextlib.py", line 17, in __enter__
    return self.gen.next()
  File "C:\b\s\swarming_bot.1.zip\client\cipd.py", line 398, in get_client
    with version_cache.getfileobj(version_digest) as f:
  File "C:\b\s\swarming_bot.1.zip\client\local_caching.py", line 564, in getfileobj
    self._used.append(self._lru[digest])
  File "C:\b\s\swarming_bot.1.zip\utils\lru.py", line 56, in __getitem__
    return self._items[key][0]
KeyError: 'e98c19a51e39462ccff52ca52af6dd40e68b6546'
Sending the crash report ... done.
Report URL: https://isolateserver.appspot.com/restricted/ereporter2/errors/5696233700065280
'e98c19a51e39462ccff52ca52af6dd40e68b6546'
"""

https://ci.chromium.org/p/chromium/builders/luci.chromium.try/win10_chromium_x64_rel_ng/128076

See webui_polymer2_browser_tests failure.