Index: django/core/handlers/base.py
===================================================================
--- django/core/handlers/base.py	(revision 10037)
+++ django/core/handlers/base.py	(working copy)
@@ -50,7 +50,7 @@
                 continue
 
             if hasattr(mw_instance, 'process_request'):
-                self._request_middleware.append(mw_instance.process_request)
+                _request_middleware.append(mw_instance.process_request)
             if hasattr(mw_instance, 'process_view'):
                 self._view_middleware.append(mw_instance.process_view)
             if hasattr(mw_instance, 'process_response'):