Cache rewrite rules. Add WP_Rewrite::flush_rules(). fixes #2155

git-svn-id: https://develop.svn.wordpress.org/trunk@3373 602fd350-edb4-49c9-b593-d223f7449a82

wp-admin/options.php

@@ -66,7 +66,7 @@ case 'update':
 			// If siteurl or home changed, reset cookies.
 			if ( get_settings('siteurl') != $old_siteurl || get_settings('home') != $old_home ) {
 				// If home changed, write rewrite rules to new location.
-				save_mod_rewrite_rules();
+				$wp_rewrite->flush_rules();
 				// Get currently logged in user and password.
 				get_currentuserinfo();
 				// Clear cookies for old paths.