大家应该都知道怎么添加国内pip源（主要是豆瓣和阿里云），~/.pip/pip.conf文件配置大概如下（下面注释掉了豆瓣源）：
[global]
# index-url = http://pypi.douban.com/simple
index-url = http://mirrors.aliyun.com/pypi/simple/
但是现在最新的pip要求源必须是https的，不然会报错：
The repository located at http://mirrors.aliyun.com is not a trusted or secure host and is being ignored. If this repository is available via HTTPS it is recommended to use HTTPS instead, otherwise you may silence this warning and allow it anyways with '--trusted-host mirrors.aliyun.com'.
但是每次要加这么长的尾巴很不geek，尝试在上面pip.conf里面加上
trusted-host = mirrors.aliyun.com
居然好了，所以最终的pip.conf如下：
[global]
index-url = http://mirrors.aliyun.com/pypi/simple/
trusted-host = mirrors.aliyun.com
如果用豆瓣源，也是同理。
注意 加了trusted-host依然报这个warning 说明你电脑上存在多个 index，自己找到然后删至一个即可