Regression report generation is failing

[jdm]

+ python3 tests/wpt/reftests-report/gen.py 10b1659ee1b5430bc25dc5d851e4ee76767560b2 856f03ae7595e90b86d6f1c7b64fae1f9f3aa95a
Fetching https://community-tc.services.mozilla.com/api/index/v1/task/project.servo.linux_x64_wpt_1.10b1659ee1b5430bc25dc5d851e4ee76767560b2
Fetching https://community-tc.services.mozilla.com/api/queue/v1/task/IeHPlo7qSKKRQBP_y-Zw3Q
Fetching https://community-tc.services.mozilla.com/api/index/v1/task/project.servo.linux_x64_wpt_1.10b1659ee1b5430bc25dc5d851e4ee76767560b2/artifacts/public/test-wpt.log
Traceback (most recent call last):
  File "tests/wpt/reftests-report/gen.py", line 162, in <module>
    sys.exit(main(*sys.argv[1:]))
  File "tests/wpt/reftests-report/gen.py", line 65, in main
    failures_2013 = {url for url, _ in failing_reftests("linux_x64", source)}
  File "tests/wpt/reftests-report/gen.py", line 65, in <setcomp>
    failures_2013 = {url for url, _ in failing_reftests("linux_x64", source)}
ValueError: too many values to unpack (expected 2)
[taskcluster 2020-05-07 06:10:36.548Z] === Task Finished ===

This is a regression from #26437. cc @SimonSapin