NixOS/nixos — pull request #77 by rickynils (2013-01-28 15:18:37+00:00)
Title: Parameterise the path to nixpkgs.

This makes it possible to build several NixOS systems that use different
nixpkgs in the same nix-build invocation. Today, you can't do that since
the path reference is hard-coded in lib/eval-config.nix.