当我们在Linux下开发中，经常会遇到下边的问题：
[root@bpj soft]# git clone https://github.com/longxinH/xhprof.git ./xhprof
Initialized empty Git repository in /soft/xhprof/.git/
error: while accessing https://github.com/longxinH/xhprof.git/info/refs
fatal: HTTP request failed
遇到类似问题我们可以尝试更新nss来解决
yum update nss nss-util nspr
yum update curl