NETTY-407 HttpTunnelingClientSocketChannel failed close() is not sent to

calling futures.

* HttpTunnelingClientSocketChannel.writeLastChunk should return a failed
future instead of raising an exception.

src/main/java/org/jboss/netty/channel/socket/http/HttpTunnelingClientSocketChannel.java

@@ -254,7 +254,7 @@ class HttpTunnelingClientSocketChannel extends AbstractChannel
 
     private ChannelFuture writeLastChunk() {
         if (!requestHeaderWritten) {
-            throw new NotYetConnectedException();
+            return failedFuture(this, new NotYetConnectedException());
         } else {
             return realChannel.write(HttpChunk.LAST_CHUNK);
         }