如何将fork的project 更新到最新（how to make your forked project to up-to-date. )

我有个项目，去年forked，今年重新捡起来，打算弄一下。( Today I am going to continue one of my forked projects that created last year)

git的原理是： 在远程可以有多个 repo (最熟悉的就是 origin 啦). 所以，我们只要加入想merge的 remote  repo就可以了。( To make its code to the latest, I have to merge the original remote repo to my remote repo. )

$ git remote add root_origin https://github.com/refinery/refinerycms.git
$ git pull root_origin master:master ( means merge the master from root_origin to local's master)
$ (manually merge) 
$ git push origin master:master( push local's commits to your origin remote repo)

refer to : http://stackoverflow.com/questions/9529497/what-is-origin-in-git