Drop request in the client stage if there is no contact replica

There's no need for the current replica to further process the
request.

src/refit/replica/client/REFITClientStage.java

@@ -159,7 +159,7 @@ public class REFITClientStage extends REFITStage {
 					replica.mac.appendUnicastMAC(wrapper, contactReplica);
 
 					replica.replicaUnicast(wrapper, contactReplica);
-				} else {
+				} else if (contactReplica >= 0) {
 					replica.replicaUnicast(request, contactReplica);
 				}
 			} else {