Was building fennec on win32 and it fails on redit since bug 753123 landed.
Created attachment 636162 [details] [diff] [review] Patch v1.
We don't build xulrunner on normal win32 builds so that's probably why we haven't seen it yet.
I think this bug was caused by the change in bug 760995: https://hg.mozilla.org/mozilla-central/rev/14b79d264b0b
Ah nice find, makes sense.