update: Some people prefer another solution: commit (git svn dcommit) from Trunk-Blue. The process is simliar, the benefit is that you do not have to switch between Green and Blue folders.
I am now working on a web project. Our local CI build takes more than 20 minutes now. While we are working to speed up the build, I am also trying to create a local build folder, so that I can still work (modify code) when the local build is running. The idea is quite simple. We have two folders, one for committing (named trunk-green) and the other for editing (named trunk-blue). When we want to run local build we sync the code from the committing folder. However the solution is not that simple, when it comes to a team of more than 10 developers and QAs working on it. I met a lot of problems, and I am not confident to promote it to others yet now. Anyway, I will record what I learned during working out the final solution.
1. How to force git to overwrite local files on pull?
当双方代码有冲突时，直接git pull会报错。可以使用git fetch --all，然后git reset --hard origin/master。见http://stackoverflow.com/questions/1125968/force-git-to-overwrite-local-files-on-pull
下一步问题，为什么参考链接中出现：error: Untracked working tree file 'public/images/icon.gif' would be overwritten by merge.。