bpo-46080: fix argparse help generation exception in edge case (GH-30111)


Fix an uncaught exception during help text generation when
argparse.BooleanOptionalAction is used with default=argparse.SUPPRESS
and help is specified.
(cherry picked from commit 9e87c0e03fa501fb90008547983ce4c1dcaaf90c)

Co-authored-by: Felix Fontein <felix@fontein.de>
3 files changed