Currently the `rpc-gssd.service` has a `ConditionPathExists` clause that can never be met, because it's looking for stateful data inside `/nix/store`. `auth-rpcgss-module.service` also only starts if this file exists. Fixes NixOS/nixpkgs#29509.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.