update.nix: Run update scripts in parallel

To make updating large attribute sets faster, the update scripts
are now run in parallel.

Please note the following changes in semantics:

- The string passed to updateScript needs to be a path to an executable file.
- The updateScript can also be a list: the tail elements will then be passed
  to the head as command line arguments.

2 files changed, 3 insertions, 1 deletions

diff --git a/pkgs/tools/package-management/nix-pin/default.nix b/pkgs/tools/package-management/nix-pin/default.nix
index f5d62b250e2..063c173a401 100644
--- a/pkgs/tools/package-management/nix-pin/default.nix
+++ b/pkgs/tools/package-management/nix-pin/default.nix
@@ -26,6 +26,7 @@ let self = stdenv.mkDerivation rec {
         let impl = import "${self}/share/nix/api.nix" { inherit pkgs pinConfig; }; in
         { inherit (impl) augmentedPkgs pins callPackage; };
       updateScript = ''
+        #!${stdenv.shell}
         set -e
         echo
         cd ${toString ./.}
diff --git a/pkgs/tools/package-management/nix-update-source/default.nix b/pkgs/tools/package-management/nix-update-source/default.nix
index e7eb497b4b9..7584496f258 100644
--- a/pkgs/tools/package-management/nix-update-source/default.nix
+++ b/pkgs/tools/package-management/nix-update-source/default.nix
@@ -1,4 +1,4 @@
-{ lib, pkgs, fetchFromGitHub, python3Packages, nix-prefetch-scripts }:
+{ stdenv, lib, pkgs, fetchFromGitHub, python3Packages, nix-prefetch-scripts }:
 python3Packages.buildPythonApplication rec {
   version = "0.6.3";
   name = "nix-update-source-${version}";
@@ -28,6 +28,7 @@ python3Packages.buildPythonApplication rec {
         overrideSrc = drv: lib.overrideDerivation drv (orig: { inherit src; });
       };
     updateScript = ''
+      #!${stdenv.shell}
       set -e
       echo
       cd ${toString ./.}