Could you find where is the bug?

test_click_module_bug.py

from collections import defaultdict
import click

@click.group()
@click.pass_context
def cli(ctx):
    print('cli init')


@cli.group()
@click.pass_context
def debian(ctx):
    print('in debian')


@debian.command()
def list():
    print('list')
    cc = defaultdict(list)
    cc[0]

cli()

# $ python test.py debian list
# cli init
# in debian
# list
# Usage: test.py [OPTIONS]
# Try 'test.py --help' for help.
#
# Error: Got unexpected extra arguments (debian list)