Both opt and debug runs increased their runtime by 20+min after the MSG refactor landed (bug 848954). Looking at the logs, it appears that tests (many in OS.File, like test_removeDir.js) went from a ~30s runtime to 4+min. This is causing us to hit both the global 120min timeout as well as the individual 5min test timeout. https://tbpl.mozilla.org/php/getParsedLog.php?id=46833259&tree=Mozilla-Inbound We have a reconfig coming shortly that'll split debug xpcshell into 2 chunks, which will take care of the global timeouts. As odious as it is to me, I think that for now, we need to bump the test timeout as well as the reasons for big increase in test runtime are unclear.

The chunking change is live now, so hopefully we have green on this push. https://hg.mozilla.org/integration/mozilla-inbound/rev/90cbae5b66af

This bug is as fixed as it's going to be. There are follow-up bugs filed for various slow tests that need more investigation.