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

ChangeLog

@@ -31,6 +31,7 @@
 	  incoming connection
 	* added more detailed instrumentation of the disk I/O thread
 
+	* fixed issue where trackers wouldn't tried immediately when the previous one failed
 	* fixed synchronization issue between download queue and piece picker
 	* fixed bug in udp tracker scrape response parsing
 	* fixed bug in the disk thread that could get triggered under heavy load

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());
 	}