Sorry for the time spent on this, Paolo. Late beta simulation with a backout of https://hg.mozilla.org/mozilla-central/rev/724652219657 / bug 1514853 points to that bug (none of the oranges have a failure message for this test). Ehsan, please take a look. This permafails on beta.
Bug 1516340 Comment 7 Edit History
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Sorry for the time spent on this, Paolo. Late beta simulation with a backout of https://hg.mozilla.org/mozilla-central/rev/724652219657 / bug 1514853 points to that bug (none of the oranges have a failure message for this test): https://treeherder.mozilla.org/#/jobs?repo=try&revision=a45702316af9a507640676f60b2847323afe2d6a Ehsan, please take a look. This permafails on beta.