--- argparse.py.orig	2012-03-23 15:10:02.000000000 +0900
+++ argparse.py	2012-03-23 15:56:47.000000000 +0900
@@ -1284,3 +1284,3 @@
         type_func = self._registry_get('type', action.type, action.type)
-        if not _callable(type_func):
+        if not _callable(type_func) or type_func == bool:
             raise ValueError('%r is not callable' % (type_func,))