@xtreak , sorry, you're right, I pasted a wrong traceback.
This is original traceback:

Exception:
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/pip/basecommand.py", line 215, in main
    status = self.run(options, args)
  File "/usr/lib/python2.7/site-packages/pip/commands/install.py", line 346, in run
    requirement_set.prepare_files(finder)
  File "/usr/lib/python2.7/site-packages/pip/req/req_set.py", line 380, in prepare_files
    ignore_dependencies=self.ignore_dependencies))
  File "/usr/lib/python2.7/site-packages/pip/req/req_set.py", line 666, in _prepare_file
    check_dist_requires_python(dist)
  File "/usr/lib/python2.7/site-packages/pip/utils/packaging.py", line 48, in check_dist_requires_python
    feed_parser.feed(metadata)
  File "/usr/lib64/python2.7/email/feedparser.py", line 177, in feed
    self._input.push(data)
  File "/usr/lib64/python2.7/email/feedparser.py", line 99, in push
    parts = data.splitlines(True)
AttributeError: 'NoneType' object has no attribute 'splitlines'


And I pasted by mistake the one I used to debug.