title: Heroku staging app is crashing (unable to read environments/staging.rb)
body: <p>I had a production app on Heroku - productionapp.heroku.com</p>
  
  <p>So, I followed the steps to create a staging app for it:</p>
  
  <pre><code>1. heroku create stagingapp  --remote staging
  2. heroku config:add RACK_ENV=staging  --app stagingapp
  3. heroku addons:add mongohq:free  --app stagingapp
  4. In config/mongoid.yml -
     add
       staging:
         uri: &lt;%= ENV['MONGOHQ_URL'] %&gt;
  5. cp config/environments/production.rb config/environments/staging.rb
  6. Add the MONGOHQ_URL in the mongohq.com connection.
  6. git push staging master
  </code></pre>
  
  <p>The staging app is continuously crashing with the following backtrace:</p>
  
  <pre><code>2011-11-21T17:43:23+00:00 app[web.1]: 
  You did not specify how you would like Rails to report deprecation notices for your staging environment,
  please set config.active_support.deprecation to :log, :notify or :stderr at config/environment
  
  2011-11-21T17:43:24+00:00 app[web.1]:
  /app/.bundle/gems/ruby/1.9.1/gems/mongoid-2.3.3/lib/mongoid/railtie.rb:64:in `block in &lt;class:Railtie&gt;':
  undefined method `values' for nil:NilClass (NoMethodError)
  
  2011-11-21T17:43:24+00:00 app[web.1]:
  from /app/.bundle/gems/ruby/1.9.1/gems/railties-3.1.1/lib/rails/initializable.rb:30:in `instance_exec'
  
  2011-11-21T17:43:24+00:00 app[web.1]:
  from /app/.bundle/gems/ruby/1.9.1/gems/railties-3.1.1/lib/rails/initializable.rb:30:in `run'
  
  2011-11-21T17:43:24+00:00 app[web.1]:
  from /app/.bundle/gems/ruby/1.9.1/gems/railties-3.1.1/lib/rails/initializable.rb:55:in `block in run_initialize
  </code></pre>
  
  <p>I have tried and retried these steps again and again and end up hitting the same error.
  It would be great if you could help me out!</p>