In bug 912121, I am moving all DevTools files up to /devtools. I am currently blocked on a test failure in OS.File that seems unrelated to my changes. On Linux 32 & 64 (debug only, opt is fine), the test test_osfile_comms.xul permafails. Other platforms are fine for both debug and opt. Here's an example try run: https://treeherder.mozilla.org/#/jobs?repo=try&revision=e0538032d629 I've added a few logging states to the test and also tried forcing the worker to terminate, but that has not helped. It's strange, because the test does call finish(), but the harness then claims the test timed out.

Yoric, are you able to spot what's going wrong here?

I've found that it is a conflict with DevTools tests running before this one, as disabling all DevTools chrome tests fixes the issue. Currently continuing to bisect the test dirs to learn more. If only it would repro locally... :(

I can't see anything obviously wrong. Perhaps one of the DevTools tells is injecting something on workers? I'd suggest finding out if DevTools does something fishy that could possibly reveal/hide a bug, but if this is too much of an annoyance, I can try and port this test to a xpcshell test. It was written as a mochitest before xpcshell had access to workers.

After several days of pulling my hair out on try, I've isolated the DevTools test responsible, so I'll just disable it: test_devtools_extensions.html So we can leave this test as is.