title: Error when trying to upgrade a python package
body: <p>I have git pulled a python package (I think that is the correct terminology) that I already had installed and working.</p>
  
  <p>So now it is up to date, apparently I needed to update it using pip. I did the following:</p>
  
  <pre><code>pip install the_package --upgrade 
  </code></pre>
  
  <p>But I got the following error message:</p>
  
  <pre><code>Exception:
  Traceback (most recent call last):
  File "/opt/work/python/2.7.13/lib/python2.7/site-packages/pip/basecommand.py", line 215, in main
   status = self.run(options, args)
  File "/opt/work/python/2.7.13/lib/python2.7/site-packages/pip/commands/install.py", line 335, in run
   wb.build(autobuilding=True)
  File "/opt/work/python/2.7.13/lib/python2.7/site-packages/pip/wheel.py", line 749, in build
   self.requirement_set.prepare_files(self.finder)
  File "/opt/work/python/2.7.13/lib/python2.7/site-packages/pip/req/req_set.py", line 380, in prepare_files
   ignore_dependencies=self.ignore_dependencies))
  File "/opt/work/python/2.7.13/lib/python2.7/site-packages/pip/req/req_set.py", line 666, in _prepare_file
   check_dist_requires_python(dist)
  File "/opt/work/python/2.7.13/lib/python2.7/site-packages/pip/utils/packaging.py", line 48, in check_dist_requires_python
   feed_parser.feed(metadata)
  File "/opt/work/python/2.7.13/lib/python2.7/email/feedparser.py", line 177, in feed
   self._input.push(data)
  File "/opt/work/python/2.7.13/lib/python2.7/email/feedparser.py", line 99, in push
   parts = data.splitlines(True)
  AttributeError: 'NoneType' object has no attribute 'splitlines'
  </code></pre>
  
  <p>I'm not sure what the problem is. Could someone please point me in the right direction?</p>