Don't teleport entities that are considered dead. Addresses BUKKIT-1331

Teleportation should never be processed on dead entities. If you wish
to teleport an entity, do it on a living entity. If you wish to
teleport a player, set their respawn location in PlayerRespawnEvent.

src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java

@@ -41,6 +41,7 @@ import org.bukkit.entity.Projectile;
 import org.bukkit.entity.SmallFireball;
 import org.bukkit.entity.Snowball;
 import org.bukkit.entity.WitherSkull;
+import org.bukkit.event.player.PlayerTeleportEvent;
 import org.bukkit.inventory.EntityEquipment;
 import org.bukkit.potion.PotionEffect;
 import org.bukkit.potion.PotionEffectType;
@@ -346,4 +347,13 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
     public boolean getCanPickupItems() {
         return getHandle().canPickUpLoot;
     }
+
+    @Override
+    public boolean teleport(Location location, PlayerTeleportEvent.TeleportCause cause) {
+        if (getHealth() == 0) {
+            return false;
+        }
+
+        return super.teleport(location, cause);
+    }
 }