Index: src/wp-includes/query.php
===================================================================
--- src/wp-includes/query.php	(revision 28220)
+++ src/wp-includes/query.php	(working copy)
@@ -4361,8 +4361,7 @@
 	$page = get_query_var('page');
 	if ( ! $page )
 		$page = 1;
-	if ( is_single() || is_page() || is_feed() )
-		$more = 1;
+	$more = ( is_single( $id ) || is_page( $id ) || is_feed() ) ? 1 : 0;
 	$content = $post->post_content;
 	if ( false !== strpos( $content, '<!--nextpage-->' ) ) {
 		if ( $page > 1 )