title: Intermittent Error during WebSocket handshake: Unexpected response code: 400 on CloudBees
body: <p>I am running a websocket app on CloudBees - and I intermittently see: </p>
  
  <pre><code>Error during WebSocket handshake: Unexpected response code: 400
  </code></pre>
  
  <p>I have told it to use http 1.1 to allow Upgrades via: </p>
  
  <pre><code>bees app:proxy:update http_version=1.1
  </code></pre>
  
  <p>And it works, but I sometimes see the error (not always). </p>