How to ignore a gem per computer?
<p>By some reason some of the developers use a gem and the others don't.</p>

<p>Sometimes I met code like that:</p>

<pre><code>if File.exist?('USE_MY_GEM')
  gem 'my_gem'
end
</code></pre>

<p>and <code>USE_MY_GEM</code> written in <code>.gitignore</code>. But I believe this is not very good practice.</p>

<p>How to turn a gem off / on for a specific machine?</p>