[3.12] gh-96310: Fix a traceback in argparse when all options in a mutually exclusive group are suppressed (GH-96311) (GH-115767)

Reproducer depends on terminal size - the traceback occurs when there's
an option long enough so the usage line doesn't fit the terminal width.
Option order is also important for reproducibility.

Excluding empty groups (with all options suppressed) from inserts
fixes the problem.
(cherry picked from commit 5f7df88821)

Co-authored-by: Daniel Mach <daniel.mach@suse.com>

Lib/argparse.py

@@ -415,6 +415,8 @@ class HelpFormatter(object):
                             suppressed_actions_count += 1
 
                     exposed_actions_count = group_action_count - suppressed_actions_count
+                    if not exposed_actions_count:
+                        continue
 
                     if not group.required:
                         if start in inserts: