Clone the vector that is passed to the VelocityEvent

nms-patches/EntityHuman.patch

@@ -1,5 +1,5 @@
---- ../work/decompile-8eb82bde//net/minecraft/server/EntityHuman.java	Sat Dec  6 21:26:20 2014
-+++ src/main/java/net/minecraft/server/EntityHuman.java	Sat Dec  6 21:26:07 2014
+--- ../work/decompile-8eb82bde//net/minecraft/server/EntityHuman.java	2014-12-07 11:26:13.489010423 +0000
++++ src/main/java/net/minecraft/server/EntityHuman.java	2014-12-07 11:25:50.801010669 +0000
 @@ -8,13 +8,27 @@
  import java.util.List;
  import java.util.UUID;
@@ -306,7 +306,7 @@
 +                            Player player = (Player) entity.getBukkitEntity();
 +                            org.bukkit.util.Vector velocity = new Vector( d0, d1, d2 );
 +
-+                            PlayerVelocityEvent event = new PlayerVelocityEvent(player, velocity);
++                            PlayerVelocityEvent event = new PlayerVelocityEvent(player, velocity.clone());
 +                            world.getServer().getPluginManager().callEvent(event);
 +
 +                            if (event.isCancelled()) {