Index: Lib/argparse.py
===================================================================
--- Lib/argparse.py	(revision 83735)
+++ Lib/argparse.py	(working copy)
@@ -385,10 +385,16 @@
                     for action in group._group_actions:
                         group_actions.add(action)
                     if not group.required:
-                        inserts[start] = '['
+                        if start in inserts:
+                            inserts[start] += ' ['
+                        else:
+                            inserts[start] = '['                        
                         inserts[end] = ']'
                     else:
-                        inserts[start] = '('
+                        if start in inserts:
+                            inserts[start] += ' ('
+                        else:
+                            inserts[start] = '('                        
                         inserts[end] = ')'
                     for i in range(start + 1, end):
                         inserts[i] = '|'