Index: wp-includes/wp-db.php
===================================================================
--- wp-includes/wp-db.php	(revision 23913)
+++ wp-includes/wp-db.php	(working copy)
@@ -536,7 +536,7 @@
 	function __construct( $dbuser, $dbpassword, $dbname, $dbhost ) {
 		register_shutdown_function( array( $this, '__destruct' ) );
 
-		if ( WP_DEBUG )
+		if ( WP_DEBUG && WP_DEBUG_DISPLAY )
 			$this->show_errors();
 
 		$this->init_charset();