Index: Lib/argparse.py
===================================================================
--- Lib/argparse.py	(revisão 86639)
+++ Lib/argparse.py	(cópia de trabalho)
@@ -1713,6 +1713,9 @@
         except ArgumentError:
             err = _sys.exc_info()[1]
             self.error(str(err))
+        except IOError:
+            err = _sys.exc_info()[1]
+            self.error(str(err))
 
     def _parse_known_args(self, arg_strings, namespace):
         # replace arg strings that are file references