dockerTools: pkgs.system -> pkgs.stdenv.hostPlatform.system

`pkgs.system` is an alias

nixos/tests/docker-tools-cross.nix

@@ -7,7 +7,7 @@ import ./make-test-python.nix ({ pkgs, ... }:
 let
 
   remoteSystem =
-    if pkgs.system == "aarch64-linux"
+    if pkgs.stdenv.hostPlatform.system == "aarch64-linux"
     then "x86_64-linux"
     else "aarch64-linux";
 
@@ -18,7 +18,7 @@ let
 
     # NOTE: Since this file can't control where the test will be _run_ we don't
     #       cross-compile _to_ a different system but _from_ a different system
-    crossSystem = pkgs.system;
+    crossSystem = pkgs.stdenv.hostPlatform.system;
   };
 
   hello1 = remoteCrossPkgs.dockerTools.buildImage {

nixos/tests/docker-tools.nix

@@ -315,7 +315,7 @@ import ./make-test-python.nix ({ pkgs, ... }: {
                 "docker inspect ${pkgs.dockerTools.examples.cross.imageName} "
                 + "| ${pkgs.jq}/bin/jq -r .[].Architecture"
             ).strip()
-            == "${if pkgs.system == "aarch64-linux" then "amd64" else "arm64"}"
+            == "${if pkgs.stdenv.hostPlatform.system == "aarch64-linux" then "amd64" else "arm64"}"
         )
 
     with subtest("buildLayeredImage doesn't dereference /nix/store symlink layers"):

pkgs/build-support/docker/examples.nix

@@ -486,7 +486,7 @@ rec {
   cross = let
     # Cross compile for x86_64 if on aarch64
     crossPkgs =
-      if pkgs.system == "aarch64-linux" then pkgsCross.gnu64
+      if pkgs.stdenv.hostPlatform.system == "aarch64-linux" then pkgsCross.gnu64
       else pkgsCross.aarch64-multiplatform;
   in crossPkgs.dockerTools.buildImage {
     name = "hello-cross";