title: How to build task 'assets:precompile'
body: <p>I'm getting that error on my production server, and can't figure out why. It happens when running this command:</p>
  
  <pre><code>bundle exec rake assets:precompile RAILS_ENV=production
  </code></pre>
  
  <p>I'm using Rails 3.1.0.rc6</p>