bzr rspush gives unprintable exception

After doing
$ bzr init-repo --rich-root-pack bzrrepo
$ cd bzrrepo
$ bzr branch -r 1 svnrepo/module
$ cd module
$ bzr pull

the following command gives the following error:

$ bzr rspush host:path
bzr: ERROR: Unprintable exception NotStandalone: dict={'_preformatted_string': None, 'location': 'file:///path/to/bzrrepo/module/'}, fmt=None

It'd be nice if this could give a somewhat more descriptive error message. :-)