Fix MissingSchema error

Downloading/unpacking behave (from -r requirements.txt (line 1))
Cleaning up...
Exception:
Traceback (most recent call last):
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/basecommand.py", line 122, in main
    status = self.run(options, args)
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/commands/install.py", line 278, in run
    requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/req.py", line 1177, in prepare_files
    url = finder.find_requirement(req_to_install, upgrade=self.upgrade)
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/index.py", line 252, in find_requirement
    for page in self._get_pages(locations, req):
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/index.py", line 387, in _get_pages
    page = self._get_page(location, req)
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/index.py", line 568, in _get_page
    session=self.session,
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/index.py", line 670, in get_page
    resp = session.get(url, headers={"Accept": "text/html"})
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/_vendor/requests/sessions.py", line 468, in get
    return self.request('GET', url, **kwargs)
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/download.py", line 237, in request
    return super(PipSession, self).request(method, url, *args, **kwargs)
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/_vendor/requests/sessions.py", line 422, in request
    prep = self.prepare_request(req)
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/_vendor/requests/sessions.py", line 360, in prepare_request
    hooks=merge_hooks(request.hooks, self.hooks),
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/_vendor/requests/models.py", line 294, in prepare
    self.prepare_url(url, params)
  File "/Users/matteo/.virtualenvs/lista-spesa/lib/python3.4/site-packages/pip/_vendor/requests/models.py", line 345, in prepare_url
    "Perhaps you meant http://{0}?".format(url))
pip._vendor.requests.exceptions.MissingSchema: Invalid URL '/Users/matteo/.pip/wheels': No schema supplied. Perhaps you meant http:///Users/matteo/.pip/wheels?

Storing debug log for failure in /Users/matteo/.pip/pip.log