Description:
------------
It should be documented that, in some circumstances, the "stream_seek"
method isn't called in response to fseek.

As example:

// fseek will be called in response to fseek
$fp = fopen('mfx://test', 'w');
fwrite($fp, '12345678');
fseek($fp, 1, SEEK_CUR);
fclose($fp);


// fseek will not be called in response to fseek
$fp = fopen('mfx://test', 'w');
fwrite($fp, '12345678');
fread($fp, 2);
fseek($fp, 1, SEEK_CUR);
fclose($fp);

This is pointed out by Gustavo on the internals list:
http://news.php.net/php.internals/54999