have optimization is now optional, but on by default

include/libtorrent/session_settings.hpp

@@ -100,6 +100,7 @@ namespace libtorrent
 			, peer_connect_timeout(10)
 			, ignore_limits_on_local_network(true)
 			, connection_speed(20)
+			, send_redundant_have(false)
 #ifndef TORRENT_DISABLE_DHT
 			, use_dht_as_fallback(true)
 #endif
@@ -212,6 +213,12 @@ namespace libtorrent
 		// are made per second.
 		int connection_speed;
 
+		// if this is set to true, have messages will be sent
+		// to peers that already have the piece. This is
+		// typically not necessary, but it might be necessary
+		// for collecting statistics in some cases. Default is false.
+		bool send_redundant_have;
+
 #ifndef TORRENT_DISABLE_DHT
 		// while this is true, the dht will note be used unless the
 		// tracker is online

src/peer_connection.cpp

@@ -338,7 +338,8 @@ namespace libtorrent
 	{
 		// optimization, don't send have messages
 		// to peers that already have the piece
-		if (has_piece(index)) return;
+		if (!m_ses.settings().send_redundant_have
+			&& has_piece(index)) return;
 
 #ifdef TORRENT_VERBOSE_LOGGING
 		(*m_logger) << time_now_string()