letsencrypt更换pip源
vim letsencrypt-auto
将DEFAULT_INDEX_BASE = 'https://pypi.python.org'改为DEFAULT_INDEX_BASE = 'http://mirrors.aliyun.com/pypi'
vim letsencrypt-auto
将DEFAULT_INDEX_BASE = 'https://pypi.python.org'改为DEFAULT_INDEX_BASE = 'http://mirrors.aliyun.com/pypi'