gistfile1.txt

function change_aggregator_remote_get_url($url){
   $parse = parse_url($url);
   return str_replace($parse['host'], "localhost", $url);
}
add_filter('aggregator_remote_get_url', 'change_aggregator_remote_get_url');


function change_aggregator_remote_get_args($args, $url){

    $parse = parse_url($url);
    $args['blocking'] = true; // Not required for us
    $headers          = (array)$args['headers'];
    $headers['host']  = $parse['host'];
    $args['headers']  = $headers;
    return $args;
}

add_filter('aggregator_remote_get_args', 'change_aggregator_remote_get_args', 10, 2);