We only really have one branch "master". We encourage the engineers to push small changes, behind config flags if necessary, all the time so there is never any huge merge conflicts, etc. This also means you don't push your code to master until you are up in our push queue.

We've also had Jenkins set up for a long time now, we just used LXC to drastically improve our performance and scalability.

Here is an old blog post explaining some of how it all works: http://codeascraft.com/2011/04/20/divide-and-concur/