gh-113008: Correct argparse usage output for required, mutually exclusive groups

[paytonward6]

Prior to fix, a mutually exclusive group that contained a positional would not be printed properly when the positional is not defined first. Instead, it would completely ignore the mutual exclusiveness in the usage output.

For example:

parser = ArgumentParser(prog="PROG")
group = parser.add_mutually_exclusive_group(required=True)
group.add_argument("--foo")
group.add_argument("bar", nargs="?")
parser.parse_args()

would have a usage line of:

usage: PROG [-h] (--foo FOO | bar)

while

parser = ArgumentParser(prog="PROG")
group = parser.add_mutually_exclusive_group(required=True)
group.add_argument("bar", nargs="?")
group.add_argument("--foo")
parser.parse_args()

would have a usage line of:

usage: PROG [-h] [--foo FOO] [bar]

• Issue: argparse drops "|" when a positional, then a special "-" argument (order-sensitive), are defined in a mutually exclusive group #113008

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[serhiy-storchaka]

Thank you @paytonward6. LGTM.

[serhiy-storchaka]

There are some conflicts. Please merge the main branch into your branch.

[serhiy-storchaka]

Thank you for your contribution @paytonward6.

[paytonward6]

Thanks for the help @serhiy-storchaka, I appreciate it