fix reference to perfstats

relay.py

@@ -903,7 +903,7 @@ class RelayChannelManager(ChannelManager):
             # 2. blinding each of the client's public keys to send to the next
             #    hop.
             idx, blinded_client_pubkey = Sphinx.server(msg.client_path_selection_key,
-            self.path_selection_key, b'circuit', False, perfstats)
+            self.path_selection_key, b'circuit', False, self.perfstats)
 
             sys.exit("TODO convert shared secret into integer type modulo alpha")
             nexthop = self.relaypicker.pick_relay_by_uniform_index(idx)