tests.*: extend the existing config

pkgs/build-support/fetchgit/tests.nix

@@ -1,4 +1,6 @@
 {
+  stdenv,
+  config,
   runCommand,
   testers,
   fetchgit,
@@ -239,8 +241,11 @@
   withGitConfig =
     let
       pkgs = import ../../.. {
-        config.gitConfig = {
-          url."https://github.com".insteadOf = "https://doesntexist.forsure";
+        system = stdenv.hostPlatform.system;
+        config = config // {
+          gitConfig = {
+            url."https://github.com".insteadOf = "https://doesntexist.forsure";
+          };
         };
       };
     in

pkgs/test/config.nix

@@ -1,5 +1,6 @@
 {
   lib,
+  config,
   pkgs,
   ...
 }:
@@ -17,7 +18,7 @@ lib.recurseIntoAttrs {
     let
       pkgs' = import ../.. {
         system = pkgs.stdenv.hostPlatform.system;
-        config = {
+        config = config // {
           permittedInsecurePackages = builtins.seq pkgs'.glibc.version [ ];
         };
       };

pkgs/test/cross/default.nix

@@ -1,4 +1,8 @@
-{ pkgs, lib }:
+{
+  pkgs,
+  config,
+  lib,
+}:
 
 let
 
@@ -78,6 +82,7 @@ let
           crossPkgs = import pkgs.path {
             localSystem = { inherit (pkgs.stdenv.hostPlatform) config; };
             crossSystem = crossSystemFun system;
+            inherit config;
           };
 
           emulator = crossPkgs.stdenv.hostPlatform.emulator pkgs;

pkgs/test/stdenv/default.nix

@@ -5,6 +5,7 @@
   stdenv,
   pkgs,
   lib,
+  config,
   testers,
 }:
 
@@ -20,7 +21,7 @@ let
   # use a early stdenv so when hacking on stdenv this test can be run quickly
   bootStdenv = earlyPkgs.stdenv.__bootPackages.stdenv.__bootPackages.stdenv or earlyPkgs.stdenv;
   pkgsStructured = import pkgs.path {
-    config = {
+    config = config // {
       structuredAttrsByDefault = true;
     };
     inherit (stdenv.hostPlatform) system;