There's quite a number of these errors in this [1] log file. I'm not sure why this happens, seems to be a windows-only thing. [1] https://tbpl.mozilla.org/php/getParsedLog.php?id=25799357&tree=Try&full=1

Windows is the only OS that has issues with removing files that are still open by a process. If this turns out to be a blocker we can just rip out all the leak logging code from the xpcshell harness. We're not actually using it for anything useful (we don't fail xpcshell tests for leaking), and nobody has been motivated to make that happen, so it's just taking up space. http://mxr.mozilla.org/mozilla-central/source/testing/xpcshell/runxpcshelltests.py#932 and the related bits.

Here's a try run without the leaklog bits. It also contains the other patches, tbpl doesn't show them. https://tbpl.mozilla.org/?tree=Try&rev=73c453ce4366

Had a bug in that one. https://tbpl.mozilla.org/?tree=Try&rev=b44562a72973

Actually it turns out that the mozcrash patches don't play nice with the current status of the parxpc harness, so here'a a try run without them https://tbpl.mozilla.org/?tree=Try&rev=46cdab537143

It seems that this fixes our problem. I retriggered a few runs to make sure.

As discussed on IRC, will take out the leak log parts in the parxpc patch.