brlaser drivers not appearing

[wagnerf42]

Issue description

brlaser drivers don't appear in cups driver list on localhost:631

Steps to reproduce

I have the following in my nix config file:
services.printing.drivers = [
pkgs.brlaser
];

adding a printer on cups web interface I don't find any brother driver.

If I go to:
/nix/store/mkx64r0yia66jj0ahmfcvfly81g35zjw-brlaser-4
it contains a strange '$out' directory

Technical details

• system: "x86_64-linux"
• host os: Linux 4.14.76, NixOS, 18.09.932.09195057114 (Jellyfish)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.1.1
• channels(wagnerf): ""
• channels(root): "nixos-18.09.932.09195057114"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos