Index: src/wp-includes/capabilities.php
===================================================================
--- src/wp-includes/capabilities.php	(revision 32109)
+++ src/wp-includes/capabilities.php	(working copy)
@@ -1279,7 +1279,7 @@
 	case 'edit_plugins':
 	case 'edit_themes':
 		// Disallow the file editors.
-		if ( defined( 'DISALLOW_FILE_EDIT' ) && DISALLOW_FILE_EDIT )
+		if ( !defined( 'DISALLOW_FILE_EDIT' ) || ( defined( 'DISALLOW_FILE_EDIT' ) && false != DISALLOW_FILE_EDIT ) )
 			$caps[] = 'do_not_allow';
 		elseif ( defined( 'DISALLOW_FILE_MODS' ) && DISALLOW_FILE_MODS )
 			$caps[] = 'do_not_allow';