VCS imports fail trying to write to stderr

I've been trying to enable translations upstream imports sharing for a particular source package (gnome-panel), but the VCS imports keep failing [1] and have been disabled [2]

After asking on #launchpad, I'm told:

<wgrant> Two bugs.
<wgrant> launchpad isn't setting up bzrlib properly, so it's trying to write to non-existent self.stderr.
 And there's probably another bug that we can't see, because it's failing to write it to the non-existent self.stderr.

So I'm filing the Launchpad bug here (bzrlib bug 812185).

[1] http://launchpadlibrarian.net/75426231/vcs-imports-gnome-panel-master.log
[2] https://code.launchpad.net/~vcs-imports/gnome-panel/master