Hmm, this reminds me of  issue 762844 , which was an error parsing the swarming task URL.

Is parsing the URLs the right/only way to extract build/task numbers? If so, do we have any docs on the format of these URLs? @qyearsley do you have any info / recommendation from ChromOps' perspective?

This is also breaking try-flag:

$ try-flag update --flag=--root-layer-scrolls -- bug 417782 
Fetching results...
Traceback (most recent call last):
  File "/Users/skobes/chrome/src/third_party/WebKit/Tools/Scripts/try-flag", line 17, in <module>
    sys.exit(try_flag.main())
  File "/Users/skobes/chrome/src/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/try_flag.py", line 178, in main
    return TryFlag(sys.argv[1:], host, GitCL(host)).run()
  File "/Users/skobes/chrome/src/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/try_flag.py", line 156, in run
    self.update()
  File "/Users/skobes/chrome/src/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/try_flag.py", line 120, in update
    jobs = self._git_cl.latest_try_jobs(BUILDER_CONFIGS.keys())
  File "/Users/skobes/chrome/src/third_party/WebKit/Tools/Scripts/webkitpy/common/net/git_cl.py", line 170, in latest_try_jobs
    self.try_job_results(builder_names, include_swarming_tasks=False))
  File "/Users/skobes/chrome/src/third_party/WebKit/Tools/Scripts/webkitpy/common/net/git_cl.py", line 190, in try_job_results
    build_to_status[self._build(result)] = self._try_job_status(result)
  File "/Users/skobes/chrome/src/third_party/WebKit/Tools/Scripts/webkitpy/common/net/git_cl.py", line 220, in _build
    assert match, '%s did not match expected format' % url
AssertionError: https://ci.chromium.org/p/chromium/builders/luci.chromium.try/linux_chromium_rel_ng/20745 did not match expected format

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a1270f5866803eee25abdc54a24ce22bdea00c38

commit a1270f5866803eee25abdc54a24ce22bdea00c38
Author: Steve Kobes <skobes@chromium.org>
Date: Wed Nov 29 01:58:47 2017

Ignore ci.chromium.org jobs in GitCL.latest_try_jobs.

Bug:  785178 , 771438 
Change-Id: I8921095df30541830d45b959892adcc182598e5b
Reviewed-on: https://chromium-review.googlesource.com/795350
Reviewed-by: Quinten Yearsley <qyearsley@chromium.org>
Commit-Queue: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519955}
[modify] https://crrev.com/a1270f5866803eee25abdc54a24ce22bdea00c38/third_party/WebKit/Tools/Scripts/webkitpy/common/net/git_cl.py

Not sure if the CL in comment 3 fixes the issue forever (or if the swarming URL will change again in the future)...

Anyway, I think we can mark this issue as a dupe of 771438.