'Return the name of the version control backend if found at given
location, e.g. vcs.get_backend_name(\'/path/to/vcs/checkout\')'

def get_backend_name(self, location):

    for vc_type in self._registry.values():
        path = os.path.join(location, vc_type.dirname)
        if os.path.exists(path):
            return vc_type.name
    return None
