Terminé de instalar pip en linux, elpip list El comando funciona. Pero cuando se usa elpip install comando obtuvo el siguiente error:

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/basecommand.py", line 232, in main
    status = self.run(options, args)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/commands/install.py", line 339, in run
    requirement_set.prepare_files(finder)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/req/req_set.py", line 333, in prepare_files
    upgrade=self.upgrade,
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/index.py", line 305, in find_requirement
    page = self._get_page(main_index_url, req)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/index.py", line 783, in _get_page
    return HTMLPage.get_page(link, req, session=self.session)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/index.py", line 872, in get_page
    "Cache-Control": "max-age=600",
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/sessions.py", line 473, in get
    return self.request('GET', url, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/download.py", line 365, in request
    return super(PipSession, self).request(method, url, *args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/sessions.py", line 461, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/sessions.py", line 573, in send
    r = adapter.send(request, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/cachecontrol/adapter.py", line 43, in send
    resp = super(CacheControlAdapter, self).send(request, **kw)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/adapters.py", line 370, in send
    timeout=timeout
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/packages/urllib3/connectionpool.py", line 518, in urlopen
    body=body, headers=headers)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/packages/urllib3/connectionpool.py", line 322, in _make_request
    self._validate_conn(conn)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/packages/urllib3/connectionpool.py", line 727, in _validate_conn
    conn.connect()
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/packages/urllib3/connection.py", line 238, in connect
    ssl_version=resolved_ssl_version)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/packages/urllib3/util/ssl_.py", line 254, in ssl_wrap_socket
    return context.wrap_socket(sock)
  File "/usr/local/lib/python2.7/ssl.py", line 350, in wrap_socket
    _context=self)
  File "/usr/local/lib/python2.7/ssl.py", line 537, in __init__
    raise ValueError("check_hostname requires server_hostname")
ValueError: check_hostname requires server_hostname

¿Cómo puedo arreglar esto?