certbotでpyOpenSSL ImportError

いつだかのyum updateで以下のエラーを吐いて動かなくなった。

Traceback (most recent call last):
  File "/bin/certbot", line 9, in <module>
    load_entry_point('certbot==0.26.1', 'console_scripts', 'certbot')()
  File "/usr/lib/python2.7/site-packages/pkg_resources.py", line 378, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/usr/lib/python2.7/site-packages/pkg_resources.py", line 2566, in load_entry_point
    return ep.load()
  File "/usr/lib/python2.7/site-packages/pkg_resources.py", line 2260, in load
    entry = __import__(self.module_name, globals(),globals(), ['__name__'])
  File "/usr/lib/python2.7/site-packages/certbot/main.py", line 21, in <module>
    from certbot import client
  File "/usr/lib/python2.7/site-packages/certbot/client.py", line 16, in <module>
    from acme import client as acme_client
  File "/usr/lib/python2.7/site-packages/acme/client.py", line 36, in <module>
    requests.packages.urllib3.contrib.pyopenssl.inject_into_urllib3()  # type: ignore
  File "/usr/lib/python2.7/site-packages/urllib3/contrib/pyopenssl.py", line 112, in inject_into_urllib3
    _validate_dependencies_met()
  File "/usr/lib/python2.7/site-packages/urllib3/contrib/pyopenssl.py", line 147, in _validate_dependencies_met
    raise ImportError("'pyOpenSSL' module missing required functionality. "
ImportError: 'pyOpenSSL' module missing required functionality. Try upgrading to v0.14 or newer.

最終行でググるとpipで入れてるパッケージとyumでいれてるパッケージで
バージョンに差異があるためっぽい。
pipで入ってるパッケージをアップグレードする。

↓↓↓↓↓↓↓ あなたの記事の内容
$ pip uninstall requests
$ yum reinstall python-requests-toolbelt
$ pip uninstall six
$ yum reinstall python-six
$ pip uninstall urllib3
$ yum reinstall python-urllib3
───────
$ pip install --upgrade pip
$ pip install requests --ignore-installed
$ pip install --upgrade --force-reinstall 'requests==2.6.0'
↑↑↑↑↑↑↑ 編集リクエストの内容

参考URL
https://github.com/certbot/certbot/issues/5534#issuecomment-364549029