title: pip install error: "Unknown archive format: .whl"
body: <p>I'm new to virtualenv (on windows).  I'm trying to use pip (1.5) install a local wheel file, but it is failing.</p>
  
  <p>The command is:</p>
  
  <pre><code>pip install --no-index -f C:/Users/&lt;User&gt;/Download openpyxl
  </code></pre>
  
  <p>In the pip.log, I can see where it finds the correct file, but then doesn't try to install it:</p>
  
  <pre><code>  Skipping link file:///C:/Users/&lt;User&gt;/Download/openpyxl-1.7.0-py2.py3-none-any.whl; unknown archive format: .whl
  </code></pre>
  
  <p>I have wheel (version 0.22) install globally as well as in the virtual environment.  Any idea how I can get .whl to be a recognized format?</p>