Index: wp-includes/query.php
===================================================================
--- wp-includes/query.php	(revision 21656)
+++ wp-includes/query.php	(working copy)
@@ -2757,6 +2757,9 @@
 			$this->posts[$i] = sanitize_post( $post, 'raw' );
 		}
 
+		if ( empty( $post_type ) && $this->is_page )
+			$post_type = $post_type_object->name;
+
 		if ( $q['cache_results'] )
 			update_post_caches($this->posts, $post_type, $q['update_post_term_cache'], $q['update_post_meta_cache']);