title: Install a Rails gem of specific revision of a branch in Github
body: <p>I updated a gem (ajaxful_rating), it breaks my code because of a new revision. How do I specify a particular revision to reinstall the gem?
  I was trying:</p>
  
  <pre><code>gem 'ajaxful_rating', :git =&gt; 'git://github.com/edgarjs/ajaxful-rating.git', :branch =&gt; "rails3",
  :revision =&gt;'ecce22bf374caa328c087f3ca22711d1dd461906'
  </code></pre>
  
  <p>but it didn't work.</p>
  
  <p>Thank you.</p>