core: add some flakes to system registry

hosts/default.nix

@@ -14,6 +14,13 @@ let
 
       specialArgs = {
         inherit unstablePkgs;
+
+        flakes = {
+          nixpkgs = nixpkgs;
+          master = inputs.unstable;
+          nixflk = self;
+        };
+
         usr = { inherit utils; };
       };
 

profiles/core.nix

@@ -1,4 +1,4 @@
-{ config, lib, pkgs, unstablePkgs, ... }:
+{ config, lib, pkgs, unstablePkgs, flakes, ... }:
 let inherit (lib) fileContents;
 
 in {
@@ -6,6 +6,12 @@ in {
 
   nix.systemFeatures = [ "nixos-test" "benchmark" "big-parallel" "kvm" ];
 
+  nix.registry = with flakes; {
+    nixpkgs.flake = nixpkgs;
+    nixflk.flake = nixflk;
+    master.flake = master;
+  };
+
   imports = [ ../local/locale.nix ];
 
   environment = {