title: Session Data is not updating
body: <p>I m using <code>express-session</code> and <code>memcached-connect</code> package for maintaining session.
  Everything is working as expected.</p>
  
  <p>Here is my implementation:</p>
  
  <p>Middleware</p>
  
  <pre><code>app.use(session({
      rolling: true,
      secret: 'iloveexpress',
      proxy: 'true',
      store: new MemcachedStore({
          hosts: ['127.0.0.1:11211']
      }),
      cookie: {
          maxAge: 86400000,
          path: "/",
          domain: 'example.com'
      }, //1 Day
      saveUninitialized: false,
      resave: true
  }));
  </code></pre>
  
  <p>Setting Session</p>
  
  <pre><code>req.session.data = {
     id: '123,
     name: 'ABC',
     amount: 1000,
     profilePic: '/images/asd.jpg'
  }
  </code></pre>
  
  <p>Updating Session</p>
  
  <pre><code>req.session.data.amount = 500;
  </code></pre>
  
  <p>But when I update a particular data in the session, it not updating. The other time I make a request to the Api its showing the old data, i.e., <code>amount = 1000;</code></p>
  
  <p><strong>EDIT:</strong>
  console of req.session</p>
  
  <pre><code>Session {
    cookie:
     { path: '/',
       _expires: 2017-09-20T07:11:35.394Z,
       originalMaxAge: 86399951,
       httpOnly: true,
       domain: 'example.com' },
    data:
     { id: '591173362ad30b419e2c4f54',
       name: 'ABC',
       amount: 1000,
       profilePic: '/image/1496663576532Koala.jpg' } }
  </code></pre>