merged piece request fix from RC_0_16

ChangeLog

@@ -20,6 +20,7 @@
 	* fix uTP edge case where udp socket buffer fills up
 	* fix nagle implementation in uTP
 
+	* fix piece picking edge case that could cause torrents to get stuck at hash failure
 	* try unencrypted connections first, and fall back to encryption if it fails (performance improvement)
 	* add missing functions to python binding (flush_cache(), remap_files() and orig_files())
 	* improve handling of filenames that are invalid on windows

src/peer_connection.cpp

@@ -4055,6 +4055,7 @@ namespace libtorrent
 			m_last_request = now;
 			request_a_block(*t, *this);
 			if (m_disconnecting) return;
+			send_block_requests();
 		}
 
 		on_tick();