title: No relationship of type when opening Word document with Python
body: <p>When trying to open a <code>.dot</code> file with <code>python-docx</code>, I am getting the error:</p>
  
  <pre><code>KeyError: "no relationship of type 'http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument' in collection"
  </code></pre>
  
  <p>This is the code in question:</p>
  
  <pre><code>from docx import Document
  document = Document('file.dot')
  </code></pre>
  
  <p>What is the actual problem here?</p>