Description:
------------
stream_copy_to_stream() returns 0 when maxlength is bigger then the actual length. But copying is ok.

Reproduce code:
---------------
$src = fopen('http://www.php.net', 'r');
$dest = fopen('ok.txt', 'w');
echo stream_copy_to_stream($src, $dest) . " bytes copied\n";
fclose($src); fclose($dest);

$src = fopen('http://www.php.net', 'r');
$dest = fopen('BUG.txt', 'w');
echo stream_copy_to_stream($src, $dest, 100000) . " bytes copied\n"; // returns zero
fclose($src); fclose($dest);

echo filesize('ok.txt')."\n";
echo filesize('BUG.txt')."\n";


Expected result:
----------------
39821 bytes copied
39821 bytes copied
39821
39821

Actual result:
--------------
39821 bytes copied
0 bytes copied
39821
39821