joomla/joomla-platform — pull request #1221 by dianaprajescu (2012-05-25 13:24:30+00:00)
Title: Curl request() encodes $data regardless the Content-type header.

To post a file using curl the '@' prefix must be used with the file's full path. As of PHP 5.2.0, the CURLOPT_POSTFIELDS option must be an array if this prefix is used. That means the $data parameter of the request() method must not be encoded if the Content-type header is multipart/form-data.