Comment 3 for bug 30576

This is affecting a growing number of users who ctrl-c the initial push to the supermirror, and it cannot be corrected by them as they cant remove the directory on the supermirror. That fact that leaves a non-branch dir is a separate bug, but this is likely easier and quicker to fix. I think an empty dir, and a dir with .bzr or .bzr/repository existing should all be treated equally.