Hello,

My devstack stacking is failing in the following stage:

/usr/local/bin/pip2.7 install -c /opt/stack/requirements/upper-constraints.txt -U setuptools

stack@openstack1:~/devstack$ /usr/local/bin/pip2.7 install -c /opt/stack/requirements/upper-constraints.txt -U setuptools
Ignoring dnspython3: markers "python_version=='3.4'" don't match your environment
Ignoring os-win: markers "python_version=='3.4'" don't match your environment
Ignoring requestsexceptions: markers "python_version=='3.4'" don't match your environment
Exception:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/pip/basecommand.py", line 211, in main
    status = self.run(options, args)
  File "/usr/local/lib/python2.7/dist-packages/pip/commands/install.py", line 305, in run
    wb.build(autobuilding=True)
  File "/usr/local/lib/python2.7/dist-packages/pip/wheel.py", line 705, in build
    self.requirement_set.prepare_files(self.finder)
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_set.py", line 334, in prepare_files
    functools.partial(self._prepare_file, finder))
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_set.py", line 321, in _walk_req_to_install
    more_reqs = handler(req_to_install)
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_set.py", line 409, in _prepare_file
    req_to_install, finder)
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_set.py", line 365, in _check_skip_installed
    finder.find_requirement(req_to_install, self.upgrade)
  File "/usr/local/lib/python2.7/dist-packages/pip/index.py", line 486, in find_requirement
    all_versions = self._find_all_versions(req.name)
  File "/usr/local/lib/python2.7/dist-packages/pip/index.py", line 404, in _find_all_versions
    index_locations = self._get_index_urls_locations(project_name)
  File "/usr/local/lib/python2.7/dist-packages/pip/index.py", line 378, in _get_index_urls_locations
    page = self._get_page(main_index_url)
  File "/usr/local/lib/python2.7/dist-packages/pip/index.py", line 818, in _get_page
    return HTMLPage.get_page(link, session=self.session)
  File "/usr/local/lib/python2.7/dist-packages/pip/index.py", line 928, in get_page
    "Cache-Control": "max-age=600",
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/sessions.py", line 477, in get
    return self.request('GET', url, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/pip/download.py", line 373, in request
    return super(PipSession, self).request(method, url, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/sessions.py", line 465, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/sessions.py", line 594, in send
    history = [resp for resp in gen] if allow_redirects else []
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/sessions.py", line 196, in resolve_redirects
    **adapter_kwargs
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/sessions.py", line 605, in send
    r.content
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/models.py", line 750, in content
    self._content = bytes().join(self.iter_content(CONTENT_CHUNK_SIZE)) or bytes()
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/models.py", line 673, in generate
    for chunk in self.raw.stream(chunk_size, decode_content=True):
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/packages/urllib3/response.py", line 303, in stream
    for ...