以普通用户身份尝试通过 HTTPS执行curl或执行git clone某些操作时，失败并显示以下错误：
fatal: unable to access 'https://github.com/mikemackintosh/xxx/': Problem with the SSL CA cert (path? access rights?)
注意：如果我以 root 身份运行命令，它可以正常工作，但 root 不应是唯一能够通过 ssl 进行通信的用户。
所以我想，好吧，curl 在幕后做了什么：
$ GIT_CURL_VERBOSE=1 git clone https://github.com/mikemackintosh/xxx
Cloning into 'xxx'...
* Couldn't find host github.com in the .netrc file; using defaults
* Hostname was NOT found in DNS cache
* Trying 192.30.252.130...
* Connected to github.com (192.30.252.130) port 443 (#0)
* error reading ca cert file /etc/ssl/certs/ca-certificates.crt (Error while reading file.) …