gzip: add setup-hook to stop gzip from adding timestamps to headers

pkgs/tools/compression/gzip/default.nix

@@ -1,4 +1,8 @@
-{ stdenv, fetchurl, xz }:
+{ stdenv
+, fetchurl
+, xz
+, writeText
+}:
 
 stdenv.mkDerivation rec {
   pname = "gzip";
@@ -26,6 +30,12 @@ stdenv.mkDerivation rec {
     }' $out/bin/*
   '';
 
+  # set GZIP env variable to "-n" to stop gzip from adding timestamps
+  # to archive headers: https://github.com/NixOS/nixpkgs/issues/86348
+  setupHook = writeText "setup-hook" ''
+    export GZIP="-n"
+  '';
+
   meta = {
     homepage = "https://www.gnu.org/software/gzip/";
     description = "GNU zip compression program";