Conflict with systemd.sysusers

[oluceps]

NixOS/nixpkgs#270727

Reproduce

After enable:

  systemd.sysusers.enable = true;
  system.etc.overlay.enable = true;
  system.etc.overlay.mutable = false;

rebuild produces log:

warning: Git tree '/etc/nixos' is dirty
Finished at 23:17:50 after 2s
building the system configuration...
warning: Git tree '/etc/nixos' is dirty
error:
       … while calling the 'head' builtin

         at /nix/store/8mrigi3asyk7w8cbnb6khjdimi20ndlp-source/lib/attrsets.nix:960:11:

          959|         || pred here (elemAt values 1) (head values) then
          960|           head values
             |           ^
          961|         else

       … while evaluating the attribute 'value'

         at /nix/store/8mrigi3asyk7w8cbnb6khjdimi20ndlp-source/lib/modules.nix:809:9:

          808|     in warnDeprecation opt //
          809|       { value = builtins.addErrorContext "while evaluating the option `${showOption loc}':" value;
             |         ^
          810|         inherit (res.defsFinal') highestPrio;

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: The option `system.activationScripts.users' is defined multiple times while it's expected to be unique.

       Definition values:
       - In `/nix/store/7b1y8jvq8n1vqj3pgadfkv6bammk58yy-source/hosts/hastur/default.nix':
           {
             deps = [
               "agenixInstall"
             ];
           }
       - In `/nix/store/8mrigi3asyk7w8cbnb6khjdimi20ndlp-source/nixos/modules/config/users-groups.nix': ""
       Use `lib.mkForce value` or `lib.mkDefault value` to change the priority on any of these definitions.

[oluceps]

related Mic92/sops-nix@695275c