Attempt to avoid npe during handshake

patches/cpw/mods/fml/common/network/internal/HandshakeCompletionHandler.java.patch

@@ -1,18 +1,19 @@
 --- ../src-base/minecraft/cpw/mods/fml/common/network/internal/HandshakeCompletionHandler.java
 +++ ../src-work/minecraft/cpw/mods/fml/common/network/internal/HandshakeCompletionHandler.java
-@@ -13,9 +13,15 @@
+@@ -13,8 +13,14 @@
      @Override
      protected void channelRead0(ChannelHandlerContext ctx, CompleteHandshake msg) throws Exception
      {
+-        NetworkDispatcher dispatcher = ctx.channel().attr(NetworkDispatcher.FML_DISPATCHER).getAndRemove();
+-        dispatcher.completeHandshake(msg.target);
 +        // Cauldron start - attempt to fix race condition with attr being null
-+        Object attr = ctx.channel().attr(NetworkDispatcher.FML_DISPATCHER);
++        io.netty.util.Attribute<NetworkDispatcher> attr = ctx.channel().attr(NetworkDispatcher.FML_DISPATCHER);
 +        if (attr != null)
 +        {
-         NetworkDispatcher dispatcher = ctx.channel().attr(NetworkDispatcher.FML_DISPATCHER).getAndRemove();
-         dispatcher.completeHandshake(msg.target);
-     }
++        	NetworkDispatcher dispatcher = attr.getAndRemove();
++        	if (dispatcher != null) dispatcher.completeHandshake(msg.target);
++        }
 +        // Cauldron end
-+    }
+     }
  
      @Override
-     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception