Actually allow cancellation of player chat events

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

@@ -419,6 +419,7 @@ implements ICommandListener {
             PlayerChatEvent event = new PlayerChatEvent(Type.PLAYER_CHAT, player, s);
             server.getPluginManager().callEvent(event);
             s = (new StringBuilder()).append("<").append(event.getPlayer().getName()).append("> ").append(event.getMessage()).toString();
+            if (event.isCancelled()) return;
             // CraftBukkit stop
 
             a.info(s);