title: .gitignore not matching subdirectories
body: <p>I have directory tree like this:</p>
  
  <pre><code>__pycache__
  systems
      __pycache__
      ...
  components
      __pycache__
      ...
  ...
  </code></pre>
  
  <p>I tried the following <code>.gitignore</code>s to ignore all <code>__pycache__</code> directories. However, they are not working - only the first one is ignored.</p>
  
  <p><code>**/__pycache__/</code> and <code>__pycache__/</code></p>
  
  <p>How do I ignore all of them?</p>