http: fix test-http-should-keepalive.js is fail

3df7c90 was removed when conflict was resolved.

lib/http.js

@@ -1306,8 +1306,7 @@ ClientRequest.prototype.onSocket = function(socket) {
         return true;
       }
 
-      if (req.shouldKeepAlive && res.headers.connection !== 'keep-alive' &&
-          !req.upgradeOrConnect) {
+      if (req.shouldKeepAlive && !shouldKeepAlive && !req.upgradeOrConnect) {
         // Server MUST respond with Connection:keep-alive for us to enable it.
         // If we've been upgraded (via WebSockets) we also shouldn't try to
         // keep the connection open.