忘了从哪里弄来的，安装新版git的利器：

#安装Git
yum install -y epel-release
rpm -ivh https://centos6.iuscommunity.org/ius-release.rpm
yum list git2u
yum install -y git2u
git --version

可以说是见到过的最简单的办法了

如果是CentOS7，记得更改rpm :

rpm -ivh https://centos7.iuscommunity.org/ius-release.rpm