dont warn dead code for test utils

src/utils.rs

@@ -79,6 +79,7 @@ pub fn torrent_to_magnet<T: AsRef<Path>>(torrent: T) -> Result<String, Error> {
 }
 
 // Fallible: only used in tests
+#[allow(dead_code)]
 pub fn find_free_port() -> u16 {
     let bind = TcpListener::bind("127.0.0.1:0").unwrap();
     bind.local_addr().unwrap().port()