title: You have already activated X, but your Gemfile requires Y
body: <p>When running <code>rake</code> I get this error:</p>
  
  <blockquote>
    <p>You have already activated rake 0.9.2, but your Gemfile requires rake 0.8.7. Consider using bundle exec.</p>
  </blockquote>
  
  <p>Using <code>bundle exec rake</code> instead of just <code>rake</code> seems to work, but is it the best way to fix this?</p>