Description:
------------
This issue concerns only multi curl.

Single handle curl works correct and returns error no. 6 when host is not resolved.

In the same situation multi curl returns 0 with curl_errno function despite the fact that curl_error returns error message.

See codes of 2 examples below

Test script:
---------------
<?
// Create a curl handle to a non-existing location
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'http://osms.pl');

// Execute
curl_exec($ch);

// Check if any error occured
if(curl_errno($ch))
{
    echo 'Curl error: ' . curl_error($ch) . ' - ' .curl_errno($ch);
}

// Close handle
curl_close($ch);
?>

-------------------------------------------------------------------------------

<?php
// create both cURL resources
$ch1 = curl_init();

// set URL 
curl_setopt($ch1, CURLOPT_URL, "http://404.php.net/");


//create the multiple cURL handle
$mh = curl_multi_init();

curl_multi_add_handle($mh,$ch1);

$active = null;
//execute the handles
do {
    $mrc = curl_multi_exec($mh, $active);
} while ($mrc == CURLM_CALL_MULTI_PERFORM);

while ($active && $mrc == CURLM_OK) {
    if (curl_multi_select($mh) != -1) {
        do {
            $mrc = curl_multi_exec($mh, $active);
        } while ($mrc == CURLM_CALL_MULTI_PERFORM);
    }
}

echo 'Curl error: ' . curl_error($ch1) . ' - ' .curl_errno($ch1);


//close the handles
curl_multi_remove_handle($mh, $ch1);
curl_multi_close($mh);
?>


Expected result:
----------------
in first example:
Curl error: Could not resolve host: osms.pl; Host not found - 6

in second:
Curl error: Could not resolve host: (nil); Host not found - 0