升级PIP（python 2）错误

我使用的是LinuxMint18和Python2.7.12。我以前做过，没有问题，但现在不行了。当我这样做时：

sudopip安装--升级pip

它回来了

Exception:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/pip/basecommand.py", line 215, in main
    status = self.run(options, args)
  File "/usr/local/lib/python2.7/dist-packages/pip/commands/install.py", line 324, in run
    requirement_set.prepare_files(finder)
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_set.py", line 380, in prepare_files
    ignore_dependencies=self.ignore_dependencies))
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_set.py", line 620, in _prepare_file
    session=self.session, hashes=hashes)
  File "/usr/local/lib/python2.7/dist-packages/pip/download.py", line 821, in unpack_url
    hashes=hashes
  File "/usr/local/lib/python2.7/dist-packages/pip/download.py", line 659, in unpack_http_url
    hashes)
  File "/usr/local/lib/python2.7/dist-packages/pip/download.py", line 853, in _download_http_url
    stream=True,
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/sessions.py", line 521, in get
    return self.request('GET', url, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/pip/download.py", line 386, 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 508, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/sessions.py", line 618, in send
    r = adapter.send(request, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/cachecontrol/adapter.py", line 47, in send
    resp = super(CacheControlAdapter, self).send(request, **kw)
  File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/adapters.py", line 499, in send
    raise RetryError(e, request=request)
RetryError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Max retries exceeded with url: /packages/62/a1/0d452b6901b0157a0134fd27ba89bf95a857fbda64ba52e1ca2cf61d8412/pip-10.0.0-py2.py3-none-any.whl (Caused by ResponseError('too many 503 error responses',))

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PyPi几分钟前就倒下了。现在试试。你可以检查它的状态