fix bordervm in hydra

default.nix

@@ -2,13 +2,19 @@
   device
 , liminix-config ? <liminix-config>
 , nixpkgs ? <nixpkgs>
+, borderVmConf ? ./bordervm.conf.nix
 }:
 
 let
   overlay = import ./overlay.nix;
   pkgs = import nixpkgs (device.system // {
     overlays = [overlay];
-    config = {allowUnsupportedSystem = true; };
+    config = {
+      allowUnsupportedSystem = true; # mipsel
+      permittedInsecurePackages = [
+        "python-2.7.18.6"       # kernel backports needs python <3
+      ];
+    };
   });
 
   config = (pkgs.lib.evalModules {
@@ -28,6 +34,7 @@ let
     modules = [
       ({  ... } : { nixpkgs.overlays = [ overlay ]; })
       (import ./bordervm-configuration.nix)
+      borderVmConf
     ];
   }).config.system;
 in {