[minor] Listen to error events re-emitted by pool into the ClientRequest

lib/node-http-proxy.js

@@ -137,7 +137,7 @@ HttpProxy.prototype = {
       };
       
       // Add a listener for the connection timeout event
-      reverse_proxy.connection.addListener('error', error);
+      reverse_proxy.addListener('error', error);
 
       // Add a listener for the reverse_proxy response event
       reverse_proxy.addListener('response', function (response) {
@@ -173,7 +173,7 @@ HttpProxy.prototype = {
       // At the end of the client request, we are going to stop the proxied request
       req.addListener('end', function () {
         reverse_proxy.end();
-        reverse_proxy.connection.removeListener('error', error);
+        reverse_proxy.removeListener('error', error);
       });
 
       self.unwatch(req);