问题描述：
git clone 报错如下：
Initialized empty Git repository in /root/project_php/.git/
error: The requested URL returned error: 401 Unauthorized while accessing http://tone.verru.cn:88/project_php.git/info/refs
fatal: HTTP request failed
解决方法：
带着问题网上走一圈，查到资料说是 git 版本问题，建议升级到 1.8.3 以上。
shell > git --version
git version 1.7.1
# 好吧，那就升级。
shell > yum -y remove git
shell > yum -y install perl cpio autoconf tk zlib-devel libcurl-devel openssl-devel expat-devel gettext-devel perl-ExtUtils-MakeMaker
shell > cd /usr/local/src
shell > wget https://www.kernel.org/pub/software/scm/git/git-2.10.0.tar.gz
shell > tar zxf git-2.10.0.tar.gz
shell > cd git-2.10.0
shell > autoconf
shell > ./configure
shell > make
shell > make insntall
# 建议不要 ./configure; make; make install ，出问题不好排查
shell > echo "PATH=$PATH:/usr/local/bin/" >> /etc/profile; source /etc/profile
shell > git --version
git version 2.10.0
# 再来克隆，发现正常。
shell > git clone http://tone.verru.cn:88/project_php.git
过程中小问题：
1、未安装 perl-ExtUtils-MakeMaker 报错如下：
/usr/bin/perl Makefile.PL PREFIX='/usr/local' INSTALL_BASE='' --localedir='/usr/local/share/locale'
Can't locate ExtUtils/MakeMaker.pm in @INC (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at Makefile.PL line 3.
BEGIN failed--compilation aborted at Makefile.PL line 3.
make[1]: *** [perl.mak] 错误 2
make: *** [perl/perl.mak] 错误 2
2、未安装 expat-devel 报错如下：
git clone: fatal: Unable to find remote helper for 'http'
# 如果是 https 应该是未安装 libcurl-devel ，建议按照文档都装上。