Docs failing to build


In the last couple of days, the daily builds on Launchpad have been
choking on the docs. They get to "reading sources... [ 91%]
faq/howto_faq", then seemingly lock up until the queue manager aborts
the build. It claims there's 2h30 of inactivity before that happens,
so it looks like something really is wrong.

Example build log:

It appears to be this big commit which broke it (unless it was an
external factor like some change to Sphinx):

Has anyone else seen this, or do you have any ideas what might be causing it?


P.S. Apologies to anyone getting this twice.