Tarballs contain user/project/branch directory structure

Loggerhead supports downloading tarballs of arbitrary branches throught the canonical URL https://bazaar.launchpad.net/~<user>/<proj>/<branch>/tarball.

Unfortunately this is of limited use because the tarball itself contains the subdirectory tree ~<user>/<proj>/<branch>. I don't see why that is necessary and what benefits it provides.

On the other hand it makes the tarball unsuitable for many use cases - any usecase where the recepient expect the code in the root folder of the tarball. Particularly it makes tarballs created by Loggerhead unsuitable as dependency_links in a python setup.py script: easy_install expects the setup.py file of any dependency in the root folder of the tarball.

Is there a particular reason why tarballs are created like this and if not, could this be fixed?