Now, looking over the change history:
Changed 7 weeks ago by dustin Status changed from new to closed Resolution set to fixed Fix is merged - thanks for spotting that!
Oh good, they merged a fix, which means I can fix it on my system!
...except any of those details were not logged or are obscured.
bleh.
Anyway, after some digging I found the patch that fixes it in case anyone else needs a fix before the next version of buildbot is released.