Hierarchical argparse: commands only in parent help message

>>> parser.print_help()
usage: -c [-h] {extra-action,create,update} ...
positional arguments:
  {extra-action,create,update}
                        Desired action to perform
    extra-action        Do something without db
    create              Create something
    update              Update something
optional arguments:
  -h, --help            show this help message and exit


>>> parser_create.print_help()
usage: -c create [-h] -p P
optional arguments:
  -h, --help  show this help message and exit
  -p P        add db parameter


>>> parser_update.print_help()
usage: -c update [-h] -p P
optional arguments:
  -h, --help  show this help message and exit
  -p P        add db parameter


>>> parser_other.print_help()
usage: -c extra-action [-h]
optional arguments:
  -h, --help  show this help message and exit