gh-101599: argparse: simplify the option help string (GH-103372)

If the option with argument has short and long names,
output argument only once, after the long name:

   -o, --option ARG    description

instead of

   -o ARG, --option ARG    description

1 files changed, 3 insertions, 7 deletions

diff --git a/Lib/argparse.py b/Lib/argparse.py
index a32884d..9e19f39 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -564,22 +564,18 @@ class HelpFormatter(object):
             return metavar
 
         else:
-            parts = []
 
             # if the Optional doesn't take a value, format is:
             #    -s, --long
             if action.nargs == 0:
-                parts.extend(action.option_strings)
+                return ', '.join(action.option_strings)
 
             # if the Optional takes a value, format is:
-            #    -s ARGS, --long ARGS
+            #    -s, --long ARGS
             else:
                 default = self._get_default_metavar_for_optional(action)
                 args_string = self._format_args(action, default)
-                for option_string in action.option_strings:
-                    parts.append('%s %s' % (option_string, args_string))
-
-            return ', '.join(parts)
+                return ', '.join(action.option_strings) + ' ' + args_string
 
     def _metavar_formatter(self, action, default_metavar):
         if action.metavar is not None: