loomify twice explodes

exarkun@boson:/tmp$ mkdir loom-bug
exarkun@boson:/tmp$ cd loom-bug
exarkun@boson:/tmp/loom-bug$ bzr init
Created a standalone tree (format: 2a)
exarkun@boson:/tmp/loom-bug$ bzr loomify --base foo
exarkun@boson:/tmp/loom-bug$ bzr loomify --base bar
bzr: ERROR: exceptions.KeyError: u'bar'

*** Bazaar has encountered an internal error. This probably indicates a
    bug in Bazaar. You can help us fix it by filing a bug report at
        https://bugs.launchpad.net/bzr/+filebug
    attaching the crash file
        /home/exarkun/.cache/crash/bzr-20100701012400-387.crash
    and including a description of the problem.

    The crash file is plain text and you can inspect or edit it to remove
    private information.
exarkun@boson:/tmp/loom-bug$