[Nix-dev] Nix upgrade breaks packageOverrides.

[David Brown]

With nix at "nix-0.15pre20563", and the config file below in
~/.nixpkgs/config.nix, I am able to install collection-user, and have
the collection work.  With "nix-0.15pre21760", I get an error:

   error: selector `collection-user' matches no derivations

Nothing in the packageOverrides seems to be showing up.

It might be something else, since I'm moving my system profile between
before this change, and the tip at the time of writing this email.
However, my nixpkgs tree is the same both times.

-----  config.nix -----
{ pkgs, pkgsOrig }:
{
   packageOverrides = p: rec {
     user = pkgs.misc.collection {
       name = "user";
       list = [
	pkgs.file
       ];
     };
   };
}
-----  config.nix -----

Thanks,
David Brown