I managed to get the tests working again by refreshing our profiles: https://treeherder.mozilla.org/#/jobs?repo=try&revision=243c322711a8db7788de9f24a3ea3fb925f17c10 So this geckoview issue occurs when we update an existing profile. I'm guessing it's the same issue with Fenix and Fennec but I'll test that out. I'm going to land a patch that will force a new conditioned profile to be built in m-c and then remove the setting after a week (so we go back to updating existing profiles).
Bug 1645181 Comment 21 Edit History
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EDIT: Nevermind, wrong platform was being tested.