Index: wp-admin/includes/theme.php
===================================================================
--- wp-admin/includes/theme.php	(revision 19630)
+++ wp-admin/includes/theme.php	(working copy)
@@ -181,10 +181,9 @@
 	$page_templates = array();
 
 	if ( is_array( $templates ) ) {
-		$base = array( trailingslashit(get_template_directory()), trailingslashit(get_stylesheet_directory()) );
 
 		foreach ( $templates as $template ) {
-			$basename = str_replace($base, '', $template);
+			$basename = basename($template);
 
 			// don't allow template files in subdirectories
 			if ( false !== strpos($basename, '/') )