title: Why is pypandoc giving the error "RuntimeError: Missing format!" in this setup.py script?
body: <p>I have a <code>setup.py</code> script for a module. This <code>setup.py</code> script features conversion of a Markdown README file to reStructuredText (suitable for PyPI). When an attempt is made to install this module using pip (<code>sudo pip install supermodule</code>), the following error is presented:</p>
  
  <pre><code>Collecting supermodule
    Downloading supermodule-2017.1.12.2329.tar.gz
      Complete output from command python setup.py egg_info:
      Traceback (most recent call last):
        File "&lt;string&gt;", line 1, in &lt;module&gt;
        File "/tmp/pip-build-GijMOu/supermodule/setup.py", line 43, in &lt;module&gt;
          main()
        File "/tmp/pip-build-GijMOu/supermodule/setup.py", line 14, in main
          long_description = pypandoc.convert("README.md", "rst"),
        File "/usr/local/lib/python2.7/dist-packages/pypandoc/__init__.py", line 50, in convert
          outputfile=outputfile, filters=filters)
        File "/usr/local/lib/python2.7/dist-packages/pypandoc/__init__.py", line 68, in _convert
          raise RuntimeError('Missing format!')
      RuntimeError: Missing format!
  </code></pre>
  
  <p>What is going wrong and how can I fix this?</p>
  
  <p>The <code>setup.py</code> script is as follows:</p>
  
  <pre><code>#!/usr/bin/python
  # -*- coding: utf-8 -*-
  
  import os
  import pypandoc
  import setuptools
  
  def main():
  
      setuptools.setup(
          name             = "supermodule",
          version          = "2017.01.12.2329",
          description      = "super module",
          long_description = pypandoc.convert("README.md", "rst"),
          url              = "https://github.com/user/supermodule",
          author           = "A. Person",
          author_email     = "ap@sern.ch",
          license          = "GPLv3",
          py_modules       = [
                             "supermodule"
                             ],
          install_requires = [
                             "opencv",
                             "docopt",
                             "propyte",
                             "shijian",
                             "tonescale"
                             ],
          scripts          = [
                             "supermodule_test.py"
                             ],
          entry_points     = """
              [console_scripts]
              supermodule = supermodule:supermodule
          """
      )
  
  def read(*paths):
      with open(os.path.join(*paths), "r") as filename:
          return filename.read()
  
  if __name__ == "__main__":
      main()
  </code></pre>