util Host: fix a double Read Lock bug in fn Host::session_readable() (#11175)

Author: Boqin Qin

util/network-devp2p/src/host.rs

@@ -835,6 +835,7 @@ impl Host {
 				if duplicate {
 					trace!(target: "network", "Rejected duplicate connection: {}", token);
 					session.lock().disconnect(io, DisconnectReason::DuplicatePeer);
+					drop(handlers);
 					self.kill_connection(token, io, false);
 					return;
 				}