Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 16182)
+++ wp-includes/post.php	(working copy)
@@ -920,6 +920,9 @@
 	if ( empty($args->capability_type) )
 		$args->capability_type = 'post';
 
+	if ( $args->capability_type == 'post' && empty($args->capabilities) )
+		$args->map_meta_cap = true;
+
 	$args->cap = get_post_type_capabilities( $args );
 	unset($args->capabilities);