From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Alfie Cleveland <alfeh@me.com>
Date: Sun, 8 Jan 2017 04:31:36 +0000
Subject: [PATCH] Don't allow entities to ride themselves - #572


diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 3cc3ee1a997992ea53445a656d0ab9fb9e0ae9e8..d43a6fa8c25382bef7127f1106e3bde0341472b0 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -2386,6 +2386,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
     }
 
     protected boolean addPassenger(Entity entity) { // CraftBukkit
+        if (entity == this) throw new IllegalArgumentException("Entities cannot become a passenger of themselves"); // Paper - issue 572
         if (entity.getVehicle() != this) {
             throw new IllegalStateException("Use x.startRiding(y), not y.addPassenger(x)");
         } else {