[Nix-dev] Question RE adding a package to nixpkgs

[laverne]

Hi,

The steps for adding a package to nixpkgs and testing it (pulled from here: http://nixos.org/nixpkgs/manual/#chap-quick-start) are:

1. Clone nixpkgs
2. Make your changes
3. Run nix-build -A foo from the root of the cloned repository

My question is about step 3. Will the inputs for foo come from the nixpkgs that my currently running system is running on, or will they come from the nixpkgs that I have checked out? 

Thanks,
Laverne