Adding a sub command appears to cause config file to be ignored

Reproduce Bug

python source

import configargparse
def example():
    parser = configargparse.ArgumentParser(prog="test")
    parser.add_argument(
        '-e',
        '--environments',
        type=str,
        dest='environments',
        metavar='Environment',
        choices=['dev', 'test', 'beta', 'prod'],
        action='append',
        nargs='?',
        required=True,
        help="List of deployment environments to prepare"
    )
    parser.add_argument(
        '-s',
        '--solution_path',
        type=str,
        dest='solution_path',
        metavar='Solution Path',
        required=True,
        nargs='?',
        help='Path to the root of the application source files'
    )
    parser.add_argument(
        '-c',
        '--config',
        dest='my--config',
        is_config_file=True,
        nargs='?',
        help='Config file path'
    )
    command_subparsers = parser.add_subparsers(title='Commands', dest='command', required=True)
    command_subparsers.add_parser('help', help="Prints this screen")
    args = parser.parse_known_args()
    print(args)

if __name__ == '__main__':
    example()

my-config.conf source

environments = [test, beta]
solution_path = /var/PhotApp

command

$ python3 -m my-module -c ../my-config.conf help

output:

usage: test [-h] -e [Environment] -s [Solution Path] [-c [MY--CONFIG]]
            {help} ...
test: error: the following arguments are required: -e/--environments, -s/--solution_path

Bypass Bug

comment out these lines

    command_subparsers = parser.add_subparsers(title='Commands', dest='command', required=True)
    command_subparsers.add_parser('help', help="Prints this screen")

run w/ sub command

$ python3 -m my-module -c ../my-config.conf

output

(Namespace(environments=['test', 'beta'], solution_path='/var/PhotApp', **{'my--config': '../my-config.conf'}), [])

Questions

It seems to me that adding a subcommand breaks configuration parsing.

Can anyone show me why this isn’t a bug?

[Aetylus]

While the above solution does seem to work, this ends up necessitating multiple config files - one for the main parser, and then one for each of the subparsers - and multiple, unique arguments for the config file. This doesn’t seem ideal to me in that the config can’t all be read from one file. If any config file has arguments not related to its particular parser, you end up with

error: unrecognized arguments: [...]

At least for me, what would make most intuitive sense is that the config file for the main parser applies any argument values relevant to subparsers.

[moi90]

I would expect that config file sections (which are currently ignored) correspond to subcommands.