Most of our browser test suites have a --repeat option which can run tests multiple times in the same browser session. A few tests that normally run reliably fail when repeated.

Non-repeatable tests are problematic in that:

• These tests are likely modifying (and not restoring) browser state; this change in state may be unexpected by other tests run later in the same browser session, which may lead to failures (perhaps intermittent) in those other tests.
• Such tests cannot use --repeat (--runUntilFailure, --verify, etc) to help investigate intermittent failures.

I recently realized there is an easy way to find such non-repeatable tests en-masse. I'll do that and report finding in individual bugs, in hopes of having those tests updated so that they can be repeated reliably.

https://treeherder.mozilla.org/#/jobs?repo=try&revision=69de0b755b3b5a885a5487126d898e24e5e3c4b5

That try run hit 111 test failures on just one platform, with repeat=1. I wasn't expecting that many. I wonder if follow-up on this issue is feasible...

Because this bug's Severity has not been changed from the default since it was filed, and it's Priority is P3 (Backlog,) indicating it has been triaged, the bug's Severity is being updated to S3 (normal.)

The meta keyword is there, the bug doesn't depend on other bugs and there is no activity for 12 months.
:ahal, maybe it's time to close this bug?

I think it's still worth having this open, but maybe I'll remove the meta keyword for now.