Index: wp-includes/wp-db.php
===================================================================
--- wp-includes/wp-db.php	(revision 15520)
+++ wp-includes/wp-db.php	(working copy)
@@ -517,7 +517,12 @@
 
 		$this->dbuser = $dbuser;
 
-		$this->dbh = @mysql_connect( $dbhost, $dbuser, $dbpassword, true );
+		if ( WP_DEBUG ) {
+			$this->dbh = mysql_connect( $dbhost, $dbuser, $dbpassword, true );
+		} else {
+			$this->dbh = @mysql_connect( $dbhost, $dbuser, $dbpassword, true );
+		}
+
 		if ( !$this->dbh ) {
 			$this->bail( sprintf( /*WP_I18N_DB_CONN_ERROR*/"
 <h1>Error establishing a database connection</h1>