'Returns the paths for any external backend packages.'

def _ext_backend_paths(self):

    paths = []
    for backend in settings.DATABASES.values():
        package = backend['ENGINE'].split('.')[0]
        if (package != 'django'):
            backend_pkg = __import__(package)
            backend_dir = os.path.dirname(backend_pkg.__file__)
            paths.append(os.path.dirname(backend_dir))
    return paths
