Description:
------------
Make a multiple queries that contains a buggy DML SQL command with mysqli_multi_query can cause MySQL connection closed: mysqli_ping returns false right after mysqli_multi_query() invocation.

Apache 2.2.6
MySQL 5.0.67



Reproduce code:
---------------
<?php
ini_set('mysqli.reconnect', 'Off');
$mysqli = mysqli_init();
mysqli_real_connect($mysqli, "localhost", "root", "123456", "test");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

/*

CREATE TABLE `test2` (
  `id` int(11) DEFAULT NULL,
  `username` varchar(100) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Buggy DML SQL command: INSERT INTO test2 VALUES (1008-, 'pcdinh5')
*/

$query = "INSERT INTO test2 VALUES (1007, 'pcdinh4');INSERT INTO test2 VALUES (1008-, 'pcdinh5');";

/* execute multi query */
mysqli_multi_query($mysqli, $query);

if (false === mysqli_ping($mysqli))
{
    exit('Database connection is closed');
}

?>

Expected result:
----------------
Nothing happens. If this script produces a message: Database connection is closed means there is a problem

Actual result:
--------------
This script produces a message: Database connection is closed