由于证书过期，pip 在 MacOS 上失败并出现 SSLError - 如何恢复？

在 MacOS (10.11.6) 上使用 pip 搜索或安装软件包时，我收到类似于下面重现的 SSL 错误。

python2和python3都会出现这个问题。我通过以下方式获取了版本（2.7.14 和 3.6.5）www.python.org作为框架。 pip的版本是9.0.1。该问题是新问题（2018 年 4 月），似乎与 OSX 的更新有关。

如何从这个问题中恢复？

$ pip2 search numpy

Exception:
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip/basecommand.py", line 215, in main
    status = self.run(options, args)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip/commands/search.py", line 45, in run
    pypi_hits = self.search(query, options)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip/commands/search.py", line 62, in search
    hits = pypi.search({'name': query, 'summary': query}, 'or')
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/xmlrpclib.py", line 1243, in __call__
    return self.__send(self.__name, args)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/xmlrpclib.py", line 1602, in __request
    verbose=self.__verbose
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip/download.py", line 775, in request
    headers=headers, stream=True)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip/_vendor/requests/sessions.py", line 522, in post
    return self.request('POST', url, data=data, json=json, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip/download.py", line 386, in request
    return super(PipSession, self).request(method, url, *args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip/_vendor/requests/sessions.py", line 475, in request
    resp = self.send(prep, **send_kwargs)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip/_vendor/requests/sessions.py", line 596, in send
    r = adapter.send(request, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip/_vendor/cachecontrol/adapter.py", line 47, in send
    resp = super(CacheControlAdapter, self).send(request, **kw)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip/_vendor/requests/adapters.py", line 497, in send
    raise SSLError(e, request=request)
SSLError: [SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:661)

有两种方法可以解决此问题。

解决方案1。正如可以读到的here，Python.org 网站停止了对旧 TLS 版本的支持，这打破了pip < 9.0.3。提供了新版本的 pip，但由于无法简单地通过损坏的 pip 进行更新，因此必须引导安装。这对我有用：

# For python2
curl https://bootstrap.pypa.io/get-pip.py | python2
# For python3 (haven't tested this myself)
curl https://bootstrap.pypa.io/get-pip.py | python3

这些命令的学分可返回这个帖子.

解决方案2。对于 Python 3.6 框架，一个脚本Install Certificates.command部署并安装在/Applications/Python 3.6/。执行它解决了问题，但仅限于pip3.