argcomplete: Not work with unicode as input

Example code as below:

def MyCompleter(prefix, **kwargs):
    results = ['aaa', 'bbb']
    return (c for c in results if c.startswith(prefix))

if __name__ == '__main__':
    import argparse
    import argcomplete

    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers(dest='command')
    create_parser = subparsers.add_parser('new')
    create_parser.add_argument('title')
    create_parser.add_argument('category').completer = MyCompleter
    argcomplete.autocomplete(parser)
    args = parser.parse_args()
    print args

It works as expect when all the inputs are normal characters (assume above code are wrapped in command demo):

$ ./demo.py new 'hi'
--help  -h      aaa     bbb  

When the input contains unicode, the auto completer is not working:

$ ./demo.py new '你好'

So, is this a bug or something related to the shell? I’m using zsh and argcomplete (Version: 1.9.2).