title: How to configure staging env on Heroku?
body: <p>I have a Rails app on Heroku using the Postgres 9 beta. </p>
  
  <p>I've tried to configure a staging environment using</p>
  
  <p><code>heroku config:add RACK_ENV=staging --remote staging</code></p>
  
  <p>but the app still thinks its in a production env.</p>
  
  <pre><code>Rails.env
  =&gt;"production"
  </code></pre>
  
  <p>What am I doing wrong?</p>