this seems to be more common with xorig.

for example (xorig 2):
https://treeherder.mozilla.org/jobs?repo=mozilla-central&group_state=expanded&selectedTaskRun=U4ajMMkpQsKTd7xrB7BnlA.0&test_paths=extensions%2Fformautofill%2Ftest%2Fmochitest&revision=8453a8c7c4fbec00850c934bef5be2c54fe30778&searchStr=mochitest%2Cdebug%2Cxorig%2Cosx

https://firefoxci.taskcluster-artifacts.net/U4ajMMkpQsKTd7xrB7BnlA/0/public/test_info/mochitest-plain_errorsummary.log

https://firefoxci.taskcluster-artifacts.net/U4ajMMkpQsKTd7xrB7BnlA/0/public/logs/live_backing.log

osx xorig:
TEST-START | extensions/formautofill/test/mochitest/test_address_level_1_submission.html

osx regular:
TEST-START | browser/extensions/formautofill/test/mochitest/test_address_level_1_submission.html

so we strip browser/ for xorig, that is probably somewhat related.

ok, this seems to be when the path starts with browser/, all other instances seem to be showing up. I haven't found code that specifically strips this, but there are many layers in manifest parsing, url munging, and then reporting from the test -> js harness -> stdout -> python harness -> different log files.

The severity field is not set for this bug.
:ahal, could you have a look please?

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