Description:
------------
I use CURL to get only the length of the document, I use CURLOPT_NOBODY option, it returns the response header ok, but with content-length field set to zero.

Reproduce code:
---------------
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://www.softmath.com");
curl_setopt($ch, CURLOPT_NOBODY, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_HTTPGET, true);
curl_exec($ch);
print_r(curl_getinfo($ch));
curl_close($ch);

Expected result:
----------------
Array
(
    [url] => http://www.softmath.com
    [content_type] => text/html
    [http_code] => 200
    [header_size] => 162
    [request_size] => 74
    [filetime] => -1
    [ssl_verify_result] => 0
    [redirect_count] => 0
    [total_time] => 0.297
    [namelookup_time] => 0
    [connect_time] => 0.14
    [pretransfer_time] => 0.14
    [size_upload] => 0
    [size_download] => 0
    [speed_download] => 0
    [speed_upload] => 0
    [download_content_length] => [the size of index page]
    [upload_content_length] => 0
    [starttransfer_time] => 0.297
    [redirect_time] => 0
)

Actual result:
--------------
Array
(
    [url] => http://www.softmath.com
    [content_type] => text/html
    [http_code] => 200
    [header_size] => 162
    [request_size] => 74
    [filetime] => -1
    [ssl_verify_result] => 0
    [redirect_count] => 0
    [total_time] => 0.297
    [namelookup_time] => 0
    [connect_time] => 0.14
    [pretransfer_time] => 0.14
    [size_upload] => 0
    [size_download] => 0
    [speed_download] => 0
    [speed_upload] => 0
    [download_content_length] => 0
    [upload_content_length] => 0
    [starttransfer_time] => 0.297
    [redirect_time] => 0
)