title: Importing a shared object as a module fails
body: <p>I want to create a package with the following structure:</p>
  
  <pre><code>file.py
  package_name/
  package_name/__init__.py
  package_name/module_a.py
  package_name/module_b.so
  </code></pre>
  
  <p><code>module_a</code> uses <code>module_b</code> and works well. But if I try to load the package <code>package_name</code> or the containing module <code>module_a</code> from <code>file.py</code>, an error occurs, that no <code>module_b</code> can be found. </p>
  
  <p>What am I doing wrong?</p>