* You can make branch from a commit of your local `nixos-version`. That will help you to avoid additional local compilations. Because you will recieve packages from binary cache.
*`nix-env -i pkg-name -f <path to your local nixpkgs folder>`
* add pkg ->
* Make sure it's in `pkgs/top-level/all-packages.nix`
*`nix-env -i pkg-name -f <path to your local nixpkgs folder>`
* _If you don't want to install pkg in you profile_.
*`nix-build -A pkg-attribute-name <path to your local nixpkgs folder>/default.nix` and check results in the folder `result`. It will appear in the same directory where you did `nix-build`.
* If you did `nix-env -i pkg-name` you can do `nix-env -e pkg-name` to uninstall it from your system.
* Commits must be sufficiently tested before being merged, both the master and staging branches.
* Hydra builds for master and stagingshould not be used as testing platform, it's a build farm for changes that have been already tested.
* Master should only see non-breaking commits that do not cause mass rebuilds.
* Staging should only see non-breaking mass-rebuild commits. That means it's not to be used for testing, changes must have been well tested already. [Read policy here](http://comments.gmane.org/gmane.linux.distributions.nixos/13447).
* If staging is already in a broken state, please refrain from adding extra new breakages. Stabilize it for a few days, merge into master, then resume development on staging. [Keep an eye on the staging evaluations here](http://hydra.nixos.org/jobset/nixpkgs/staging#tabs-evaluations).
* When changing the bootloader installation process, extra care must be taken. Grub installations cannot be rolled back, hence changes may break people installation forever. For any non-trivial change to the bootloader please file a PR asking for review, especially from @edolstra.