Note that for attribute-based nix-env installations, the NixOS
channel contains Nixpkgs as its "pkgs" attribute, so
$ nix-env -iA nixos.pkgs.foo
will work instead of the old
$ nix-env -iA nixpkgs_sys.foo
* Fix the path to root's channels installed in ~/.nix-defexpr.
svn path=/nixos/trunk/; revision=33823