fix(hive): misc fixes regarding the nixpkgs usage

Previously, we were using <nixpkgs> actually, we fixed liminix and this
file to ensure that we are instantiating the right nixpkgs.

This helps to deal with unexpected mass rebuilds.

Signed-off-by: Ryan Lahfa <ryan@dgnum.eu>

hive.nix

@@ -48,11 +48,8 @@ let
       name = "nixos-${v}";
     };
 
-  # Instanciate a specialized version of nixpkgs
-  mkSystemNixpkgs =
-    system: version:
-    let
-      args =
+  mkNixpkgsConfigPerSystem =
+    system: _:
     if system == "nixos" then
       { }
     else
@@ -66,6 +63,12 @@ let
           ];
         };
       };
+
+  # Instanciate a specialized version of nixpkgs
+  mkSystemNixpkgs =
+    system: version:
+    let
+      args = mkNixpkgsConfigPerSystem system version;
     in
     import (mkNixpkgs' version) args;
 
@@ -97,19 +100,31 @@ in
 {
   registry = {
     zyxel-nwa50ax = {
-      evalConfig = import "${sources.liminix}/lib/eval-config.nix" { nixpkgs = sources.nixos-unstable; };
+      evalConfig = import "${sources.liminix}/lib/eval-config.nix" {
+        nixpkgs = sources.nixos-unstable;
+      };
 
       defaults = _: {
-        nixpkgs.hostPlatform = {
+        nixpkgs = {
+          source = sources.nixos-unstable;
+          config = {
+            allowUnsupportedSystem = true; # mipsel
+            permittedInsecurePackages = [
+              "python-2.7.18.8" # Python < 3 is needed for kernel backports.
+            ];
+          };
+          hostPlatform = {
             config = "mipsel-unknown-linux-musl";
             gcc = {
               abi = "32";
               arch = "mips32"; # mips32r2?
             };
           };
+
           # It's impure, but who cares?
           # Can Flakes do that?
-        nixpkgs.buildPlatform = builtins.currentSystem;
+          buildPlatform = builtins.currentSystem;
+        };
       };
     };