Always use the set exit location for portal events. Fixes BUKKIT-3555.

src/main/java/net/minecraft/server/Entity.java

@@ -1771,7 +1771,7 @@ public abstract class Entity {
             if (event.isCancelled() || event.getTo() == null || !this.isAlive()) {
                 return;
             }
-            exit = event.useTravelAgent() ? event.getPortalTravelAgent().findOrCreate(exit) : event.getTo();
+            exit = event.useTravelAgent() ? event.getPortalTravelAgent().findOrCreate(event.getTo()) : event.getTo();
             this.teleportTo(exit, true);
         }
     }

src/main/java/net/minecraft/server/PlayerList.java

@@ -459,7 +459,7 @@ public abstract class PlayerList {
             return;
         }
 
-        exit = event.useTravelAgent() ? event.getPortalTravelAgent().findOrCreate(exit) : event.getTo();
+        exit = event.useTravelAgent() ? event.getPortalTravelAgent().findOrCreate(event.getTo()) : event.getTo();
         exitWorld = ((CraftWorld) exit.getWorld()).getHandle();
 
         Vector velocity = entityplayer.getBukkitEntity().getVelocity();