Handle errors from older versions of argparse.

IPython/config/loader.py

@@ -362,7 +362,7 b' class ArgParseConfigLoader(CommandLineConfigLoader):'
         raise NotImplementedError("subclasses must implement _add_arguments")
 
     def _parse_args(self, args):
-        """self.parser->self.parsed_data""" 
+        """self.parser->self.parsed_data"""
         self.parsed_data, self.extra_args = self.parser.parse_known_args(args)
 
     def _convert_to_config(self):

IPython/core/application.py

@@ -78,7 +78,10 b' class BaseAppConfigLoader(ArgParseConfigLoader):'
     def _add_arguments(self):
         self._add_ipython_dir(self.parser)
         self._add_log_level(self.parser)
-        self._add_version(self.parser)
+        try:  # Old versions of argparse don't have a version action
+            self._add_version(self.parser)
+        except Exception:
+            pass
 
 
 class Application(object):