Running nixpkgs-update (https://github.com/NixOS/infra/blob/main/non-critical-infra/modules/nixpkgs-update/README.md) with UPDATE_INFO: firefox-unwrapped 0 -> 1
attrpath: firefox-unwrapped
Checking auto update branch...
[version] 
[version] skipping because derivation has updateScript
[rustCrateVersion] 
[rustCrateVersion] No cargoHash found
[golangModuleVersion] 
[golangModuleVersion] Not a buildGoModule package with vendorHash
[npmDepsVersion] 
[npmDepsVersion] No npmDepsHash
[updateScript] 
[updateScript] Success
[updateScript] these 2 derivations will be built:
  /nix/store/wmxc0a0ivxv34dk2figiz8nd0ri34pz6-update-firefox-unwrapped.drv
  /nix/store/117rpggvdp0rdd26wwv1ss6apa9qg8dx-packages.json.drv
this path will be fetched (1.1 MiB download, 3.2 MiB unpacked):
  /nix/store/xzmly8r3ihh2bppycmpf5pfc29bwpl7v-xidel-unstable-2022-11-01
copying path '/nix/store/xzmly8r3ihh2bppycmpf5pfc29bwpl7v-xidel-unstable-2022-11-01' from 'https://cache.nixos.org'...
building '/nix/store/wmxc0a0ivxv34dk2figiz8nd0ri34pz6-update-firefox-unwrapped.drv'...
building '/nix/store/117rpggvdp0rdd26wwv1ss6apa9qg8dx-packages.json.drv'...

Going to be running update for following packages:
 - firefox-unwrapped-159.0.1

Press Enter key to continue...
Running update for:
Enqueuing group of 1 packages
 - firefox-unwrapped-159.0.1: UPDATING ...
 - firefox-unwrapped-159.0.1: DONE.

Packages updated!

Diff after rewrites:
diff --git a/pkgs/applications/networking/browsers/firefox/packages/firefox.nix b/pkgs/applications/networking/browsers/firefox/packages/firefox.nix
index 860399353486..c86921748517 100644
--- a/pkgs/applications/networking/browsers/firefox/packages/firefox.nix
+++ b/pkgs/applications/networking/browsers/firefox/packages/firefox.nix
@@ -9,10 +9,10 @@
 
 buildMozillaMach rec {
   pname = "firefox";
-  version = "159.0.1";
+  version = "160.0";
   src = fetchurl {
     url = "mirror://mozilla/firefox/releases/${version}/source/firefox-${version}.source.tar.xz";
-    sha512 = "e7375c0c18361b22fa1d2e6fd5f6a4ff20b22e7090a64bf32d7ef79edb0a649983439b8e6e80106fe51bb96699bdd3096c921fe198d1b460193a66d6d8f227a4";
+    sha512 = "9209a62de1ee83fe05750b77a439dc89280ebf738b5257d84af1a1faf2f4bbf505558feac126e71033c8de1a48265717c0341af4e855134e59d1b4b5b9dd820f";
   };
 
   meta = {

No auto update branch exists
Old version 159.0.1" not present in master derivation file with contents: {
  stdenv,
  lib,
  callPackage,
  fetchurl,
  nixosTests,
  buildMozillaMach,
}:

buildMozillaMach rec {
  pname = "firefox";
  version = "160.0";
  src = fetchurl {
    url = "mirror://mozilla/firefox/releases/${version}/source/firefox-${version}.source.tar.xz";
    sha512 = "9209a62de1ee83fe05750b77a439dc89280ebf738b5257d84af1a1faf2f4bbf505558feac126e71033c8de1a48265717c0341af4e855134e59d1b4b5b9dd820f";
  };

  meta = {
    changelog = "https://www.firefox.com/en-US/firefox/${version}/releasenotes/";
    description = "Web browser built from Firefox source tree";
    homepage = "http://www.mozilla.com/en-US/firefox/";
    maintainers = with lib.maintainers; [
      booxter # darwin
      hexa
    ];
    platforms = lib.platforms.unix;
    broken = stdenv.buildPlatform.is32bit;
    # since Firefox 60, build on 32-bit platforms fails with "out of memory".
    # not in `badPlatforms` because cross-compilation on 64-bit machine might work.
    maxSilent = 14400; # 4h, double the default of 7200s (c.f. #129212, #129115)
    license = lib.licenses.mpl20;
    mainProgram = "firefox";
    identifiers = {
      cpeParts = {
        inherit version;
        product = "firefox";
        update = "*";
        vendor = "mozilla";
      };
      purlParts = {
        type = "generic";
        spec = "firefox@${version}";
      };
    };
  };
  tests = {
    inherit (nixosTests) firefox;
  };
  updateScript = callPackage ../update.nix {
    attrPath = "firefox-unwrapped";
  };
}