[#390502] upgrading bzr trunk to 2a

[Martin Pool]

We've started on the conversion, but we found a bug
<https://bugs.launchpad.net/bugs/422423> (yay dogfooding) that seems
to need to be resolved before we can proceed.  It seems like this must
be a recent regression because I tried the conversion about a week ago
and it worked, and others report converting successfully recently.
So, let's fix that.

-- 
Martin <http://launchpad.net/~mbp/>