Deploy N-1. What is it and how to cook it?

Question

git

In one question here, on the toaster, I somehow read about the n-1 deployment. As I understand it, this is a kind of deployment when a new commit in the master is placed in the working version of the project, and the previous commit is not deleted, but moved somewhere else, in case you can always, probably, return it in a couple of clicks the previous version, before this commit.
Why should the question be, how can you make such a thing at home? For example if I use deployer. I thought that this approach is very safe and I would like to learn how to apply it.

Answer 1

deployer
set('keep_releases', 10);
dep rollback
documentation for wimps