title: Why does 'bundle' install production gems on my development machine?
body: <p>Gemfile says:</p>
  
  <pre><code>gem 'sqlite3', :groups =&gt; [:development, :test]
  gem 'mysql2', :group =&gt; :production
  </code></pre>
  
  <p>yet when I type <code>bundle install</code> on my development machine ALL gems are installed.</p>
  
  <p>What's wrong with my setup?</p>