title: newbie: error message when 'rake -T'
body: <p>I am using <strong>Ruby Enterprise Edition</strong> for my project. When I check all my <strong>rake task</strong> by run the command <code>rake -T</code> , I got the following error message:</p>
  
  <pre><code>You have already activated rake 0.9.2.2, but your Gemfile requires rake 0.9.2. Using bundle exec may solve this.
  </code></pre>
  
  <p>The error message implies that I can use <strong>bundle exec</strong> to solve the problem, but I am not sure how?  So, how to get rid of this error message?</p>
  
  <p><strong>------------------------------ more ---------------------------</strong></p>
  
  <p>I prefer to update my <strong>Gemfile</strong> instead of run <code>bundle exec rake -T</code>. But when I open my project Gemfile, I did not see rake 0.9.2 in my Gemfile, why the error message complains that I have it? Where could be the place I defined rake 0.9.2??</p>