[pmeunier]

One of the motivations behind Pijul was to manage custom versions of Nixpkgs while still benefiting from upstream commits. One issue that's hard with Git is that when you also want to contribute multiple changes back, you have:

1. A branch pointing to the latest nixpkgs head.

2. A branch with commit A (let's say commit A introduces a new package to nixpkgs).

3. A branch with commit B (changing some config file).

4. A branch currently at in use for your own machines, with branches 2 and 3 rebased on top of branch 1.

Every time you do anything, you'll have to remember the flow for getting the commits fetched/rebased. Which is fine if you have a DevOps team doing exactly that, but isn't too cool if you are anything other than a large company.

In Pijul, you would have a single channel (branch sort-of equivalent) and two patches (A and B) instead, which you can push independently from each other at any time if you want to contribute them back.

Darcs does the same but wouldn't scale to Nixpkgs-sized repos.