The error stack is:
Traceback (most recent call last):
  File "C:\b\swarming\w\ir\third_party\WebKit\Tools\Scripts\webkitpy\layout_tests\run_webkit_tests.py", line 615, in <module>
    sys.exit(main(sys.argv[1:], sys.stdout, sys.stderr))
  File "C:\b\swarming\w\ir\third_party\WebKit\Tools\Scripts\webkitpy\layout_tests\run_webkit_tests.py", line 59, in main
    port = host.port_factory.get(options.platform, options)
  File "C:\b\swarming\w\ir\third_party\WebKit\Tools\Scripts\webkitpy\layout_tests\port\factory.py", line 82, in get
    module = __import__(module_name, globals(), locals(), [], -1)
  File "C:\b\swarming\w\ir\third_party\WebKit\Tools\Scripts\webkitpy\layout_tests\port\android.py", line 42, in <module>
    from webkitpy.layout_tests.port import base
  File "C:\b\swarming\w\ir\third_party\WebKit\Tools\Scripts\webkitpy\layout_tests\port\base.py", line 56, in <module>
    from webkitpy.layout_tests.port import server_process
  File "C:\b\swarming\w\ir\third_party\WebKit\Tools\Scripts\webkitpy\layout_tests\port\server_process.py", line 45, in <module>
    import win32pipe
ImportError: No module named win32pipe

Hmhh, this seems like an infra error 

Swarming log: https://chromium-swarm.appspot.com/task?id=3b3754e100436510&refresh=10&show_raw=1

Thanks for triage. I was actually looking into the same issue.

The immediate problem should have been fixed by another import today: https://crrev.com/c/878006

The infra issue seems non-deterministic. A Swarming shard failed during the first import of createcredential-badargs-rp.https.html, leading to incomplete results and hence wrong baselines. The other import (which I linked above) saw no infra issues and the test was correctly rebaselined.

I've filed a bug to Swarming. And since the baseline has been fixed, I'm closing this issue by merging into the Swarming bug.