parser = argparse.ArgumentParser()
parser.add_argument('apis', nargs='*',
- choices=[group['api'] for group in SOURCES],
+ # the `[[]]` here is a workaround for python bug 9625
+ # where having `choices` breaks `nargs='*'`:
+ # https://bugs.python.org/issue9625
+ choices=[group['api'] for group in SOURCES] + [[]],
help='Only update the APIs specified.')
args = parser.parse_args()