fixed issue where trackers wouldn't tried immediately when the previous one failed

src/torrent.cpp

@@ -6493,6 +6493,8 @@ namespace libtorrent
 				m_ses.m_alerts.post_alert(scrape_failed_alert(get_handle(), r.url, ec));
 			}
 		}
+		// announce to the next working tracker
+		announce_with_tracker();
 		update_tracker_timer(time_now());
 	}