See this task: https://tools.taskcluster.net/groups/VN82D_6HRmKohjdzhtzUuA/tasks/RH70Fy9yRWy8Erb2nkP4kw/details The instance seems to die after a while, and then the task claim expires. This may be related to bug 1366288.
I am unable to download that log, it seems to go on forever ?
this appears to have fixed itself. tests still have failures, but not due to infra/instance crashing. https://treeherder.mozilla.org/#/jobs?repo=try&revision=846f648281b8c6f3458948048395f7f42c4787ea https://treeherder.mozilla.org/#/jobs?repo=try&revision=53cc6b1f7b0a3c6972aa4a2408a9adabc4ee4d53