In Android, there are many git projects in source tree. Google develops "repo" to maintain all of them.
This project could reset all the git projects to an appointed day (according to committer date.)
If you sync an Android project, you could use "python revert-day yyyy-mm-dd" to revert code. python : Please use python 2.7 to run this program. yyyy-mm-dd : Please use "-" as separator.