lighttpd - expire.url - how it realy works?

Hi.
I didn't find answer in documentation, so i'm asking you: how lighttpd is setting expire.url parameter?
Example of configuration:

Code:

$HTTP["host"]               =~ "static\.example\.tld.*" {
    server.document-root            = "/var/www_static/static.example.tld/web/"
    url.rewrite-once                = ( "^/([0-9a-z.-]*/)(.*)?$" => "/$1web/$2" )
    static-file.etags               = "disable"
    etag.use-inode                  = "disable"
    etag.use-mtime                  = "disable"
    compress.filetype               = ( "text/plain","text/css", "text/xml", "text/javascript", "application/javascript" )
    compress.allowed-encodings      = ( "gzip", "deflate" )
    $HTTP["url"]            =~ "\.(jssc|css|json)$" {
        expire.url                  = ( "" => "now plus 3600 seconds" )
    }
    $HTTP["url"]            =~ "\/latest\/" {
        expire.url                  = ( "" => "now plus 3600 seconds" )
    }
    $HTTP["url"]            =~ "\/internal\/example.cookiepolicy" {
        expire.url                  = ( "" => "now plus 86400 seconds" )
    }
    expire.url                      = ( "" => "now plus 1 years" )
    setenv.add-response-header      += (
        "Cache-Control"                => "private"
    )
}

So I have two different expire.url parameters for *.js file, one from url (now plus 3600 seconds) and second from host section (now plus 1 years).
When I make a request for js file, I have response expire: 3600s, ok, but I have also Cache-Control: private, so why lighttpd was set cache-contreol but didn't overwrite expire by "host" value?