centos 6.8 默认git 1.7.1 版本过老，安装最新版本，通过源码编译安装
卸载Centos自带的git1.7.1:
yum remove git
yum install curl-devel expat-devel gettext-devel openssl-devel zlib-devel asciidoc
yum install gcc perl-ExtUtils-MakeMaker
wget http://ftp.gnu.org/pub/gnu/libiconv/libiconv-1.14.tar.gz
tar zxvf libiconv-1.14.tar.gz
cd libiconv-1.14
./configure --prefix=/usr/local/libiconv
make && make install
下载git2.2.1并将git添加到环境变量中
wget https://github.com/git/git/archive/v2.2.1.tar.gz
tar zxvf v2.2.1.tar.gz
cd git-2.2.1
make configure
./configure --prefix=/usr/local/git --with-iconv=/usr/local/libiconv
make
make install
ln -s /usr/local/git/bin/git /usr/bin/git
git version
git version 2.2.1
参考：http://www.tuicool.com/articles/Y3eqIf