def split_repo_name(repository):
    """Take a string of the form user/repo, and return the tuple
(user, repo).  If the string does not contain the username, then just
return None for the user."""
    nameparts = repository.split('/', 1)
    if len(nameparts) == 1:
        return (None, nameparts[0])
    else:
        return (nameparts[0], nameparts[1])