I saw the following errors on win7_chromium_rel_ng a few times today:

https://ci.chromium.org/buildbot/tryserver.chromium.win/win7_chromium_rel_ng/154571

Traceback (most recent call last):
  File "C:\b\rr\tmpbfogw_\rw\checkout\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\util.py", line 151, in raises
    yield
  File "C:\b\rr\tmpbfogw_\rw\checkout\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\run.py", line 232, in run_step
    step_result = open_step.run()
  File "C:\b\rr\tmpbfogw_\rw\checkout\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\step_runner.py", line 243, in run
    return construct_step_result(rendered_step, retcode)
  File "C:\b\rr\tmpbfogw_\rw\checkout\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\step_runner.py", line 687, in construct_step_result
    result = ph.result(step_result.presentation, td)
  File "C:\b\rr\tmpbfogw_\rw\checkout\scripts\slave\.recipe_deps\recipe_engine\recipe_modules\raw_io\api.py", line 177, in result
    with open(abs_path, 'rb') as f:
IOError: [Errno 2] No such file or directory: 'c:\\users\\chrome~1\\appdata\\local\\temp\\tmpuwfmbd\\10\\layout-test-results\\virtual\\outofblink-cors\\external\\wpt\\referrer-policy\\strict-origin-when-cross-origin\\meta-referrer\\cross-origin\\http-https\\fetch-request\\upgrade-protocol.keep-origin-redirect.http-stderr.txt'


The win7_blink_rel job triggered from the same patch ran successfully:
https://ci.chromium.org/buildbot/tryserver.blink/win7_blink_rel/7106