Description:
------------
If you have a web server host that responds very quickly and you're doing a lot of requests on it, curl will eventually respond "couldn't connect to host". This happens on my Windows XP machine and Windows 2003 server, but I've been unable to reproduce on Windows 2008. If I add a delay with usleep(50000) it seems to be ok.
I'm not sure if this is by design, OS-restriction or wrong usage (I've tried forums) or actual bug. Please forgive misplacement.

To get the script below to exit with "couldn't connect to host" you need a fast responding web server host. 

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

$url = "http://www.example.com";

for ($i = 1; $i <= 6000; $i++) {

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL,$url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
    $result=curl_exec ($ch);

    if (curl_errno($ch)) {
        exit(curl_error($ch));
    } else {
        curl_close($ch);
        echo "count: $i\n";
    }
}
?> 

Expected result:
----------------
count: 1
.
.
count: 6000

Actual result:
--------------
count: 1
.
.
count 4322
couldn't connect to host