Description:
------------
When executing a stored procedure that returns multiple result sets, MySQLi driver always does an additional loop after all the result set are returned.

The last loop always returns a FALSE without any error, which indicates as if there is a query that does not return a result set in the SP. PHP Manual does not mention about the additional special loop.

SP:

CREATE PROCEDURE foo()
BEGIN
  SELECT 'foo' FROM DUAL;
  SELECT 'bar', 'bar2' FROM DUAL;
END $$

Reproduce code:
---------------
<?php

$mysqli = new mysqli("localhost", "root", "123456", "test");

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

$sql = "
DELIMITER $$
DROP PROCEDURE IF EXISTS foo $$
CREATE PROCEDURE foo()
BEGIN
  SELECT 'foo' FROM DUAL;
  SELECT 'bar', 'bar2' FROM DUAL;
END $$";

$rsCount   = 0;
$loopCount = 0;
$hasNext   = null;

if ($mysqli->real_query("CALL foo()"))
{
    do
    {
        $loopCount++;

        if ($hasNext === null)
        {
            echo 'Loop begins before any check. The first result set is available. '."\n";
        }
        else
        {
            echo "Check if there is any result set: ".(int)$hasNext." at loop ".$loopCount.". \n";
        }

        $result = $mysqli->store_result();

        if ($mysqli->errno > 0)
        {
            echo "Error: ".$mysqli->error." <<<<<<<<";
            continue;
        }

        if (is_object($result))
        {
            $rsCount++;
            // $result->free_result();
            echo 'Result set at loop '.$loopCount.'.'."\n";
        }
        else
        {
            // No result set returns
            echo 'No result set at loop '.$loopCount.'.'."\n";
        }

    } while ($hasNext = $mysqli->next_result()); // mysqli_next_result always returns true if an error occured.
}

echo "Total loop: $loopCount; Total result sets: $rsCount;";

/* close connection */
$mysqli->close();
?>


Expected result:
----------------
I created a stored procedure named foo() that is expected to return 2 result sets

DELIMITER $$
DROP PROCEDURE IF EXISTS foo $$
CREATE PROCEDURE foo()
BEGIN
  SELECT 'foo' FROM DUAL;
  SELECT 'bar', 'bar2' FROM DUAL;
END $$

The PHP code should print out:

Loop begins before any check. The first result set is available. 
Result set at loop 1.
Check if there is any result set: 1 at loop 2. 
Result set at loop 2.
Total loop: 2; Total result sets: 2;



Actual result:
--------------
The PHP code prints out:

Loop begins before any check. The first result set is available. 
Result set at loop 1.
Check if there is any result set: 1 at loop 2. 
Result set at loop 2.
Check if there is any result set: 1 at loop 3. 
No result set at loop 3.
Total loop: 3; Total result sets: 2;