由于是在Proxy的网络环境，MSYSGIT 的 git clone 总是失败。需要配置如下环境变量。
export http_proxy="http://<proxy domain name>:<port>"
之后http协议git clone没有任何问题。但是用git 协议仍旧有问题。
之后发现git push 和 git pull 经常不能work。多次尝试后发现用更全的命令行参数可以解决问题。
过程如下。
git pull --fail
git pull origin --fail
git pull git@github.com:ueddieu/mmix.git --it works.
It seems the Command line short cuts are lack of some user information, such as user name "git".
(which is kind of strange at the first glance.)
git push --fail
git push origin --fail
git push git@github.com:ueddieu/mmix.git master --it works.
Anyway, now I can check in code smoothly. :)