title: changing facebook app credentials breaking omniauth-facebook
body: <p>I set local environment variables for facebook key / secret in a file to use with <code>omniauth-facebook</code> and everything works perfectly. </p>
  
  <p>Thought it might be a good idea to have 2 facebook apps, one for dev, one for the live app. Unfortunately, when I swap out the keys in the <code>environment_variables.rb</code>, I get the following error on every auth attempt: </p>
  
  <blockquote>
    <p>OmniAuth::Strategies::Facebook::Authorization Code Error at /auth/facebook/callback</p>
  </blockquote>
  
  <p>All of the settings for the two apps are identical. I swapped back in the live app credentials, and it works again. </p>
  
  <pre><code># only change to app is changing these values
  ENV['FACEBOOK_KEY'] = '*******************'
  ENV['FACEBOOK_SECRET'] = '***********************************'
  </code></pre>
  
  <p>What I've tried:</p>
  
  <ul>
  <li>restarting server (of course)</li>
  <li>removing sandbox mode for dev app</li>
  <li>resetting secret key for dev app</li>
  <li>clearing all browsing data from browser</li>
  <li>manually deleting cookies</li>
  </ul>
  
  <p>What could be the problem?</p>