Index: wp-includes/canonical.php
===================================================================
--- wp-includes/canonical.php	(revision 13590)
+++ wp-includes/canonical.php	(working copy)
@@ -61,8 +61,10 @@
 	$redirect_url = false;
 
 	// Notice fixing
-	if ( !isset($redirect['path']) )  $redirect['path'] = '';
-	if ( !isset($redirect['query']) ) $redirect['query'] = '';
+	if ( !isset($redirect['path']) )
+		$redirect['path'] = '';
+	if ( !isset($redirect['query']) )
+		$redirect['query'] = '';
 
 	if ( is_singular() && 1 > $wp_query->post_count && ($id = get_query_var('p')) ) {
 
@@ -164,6 +166,10 @@
 				}
 
 			}
+		} elseif ( is_singular() ) {
+			$post_url = get_permalink( $wp_query->get_queried_object_id() );
+			if ( strpos($requested_url, $post_url) === false ) // If the full post's URL is not within the requested url, lets redirect there.
+				$redirect_url = $post_url;
 		}
 
 		// paging and feeds