I was going to address this as well. I've been seeing what are apparently intermittent problems with the buildbot, though I haven't seen that one before, since the beginning of the year when I started seriously looking at this stuff again.
I was able to build the docs properly on the buildbot yesterday, and in fact couldn't replicate any of the issues I had previously seen (which, in my case, seem to mostly have to do with missing CSS files). when I was talking to exarkun about it on IRC yesterday.
I'm not sure whether it has to do with the buildbot configuration, maybe stuff timing out, network issues, problems in the actual conversion process, or what.