darwin.shell_cmds: migrate to use darwin.sourceRelease

pkgs/os-specific/darwin/by-name/sh/shell_cmds/package.nix

@@ -1,6 +1,5 @@
 {
   lib,
-  apple-sdk,
   bison,
   clang,
   libedit,
@@ -8,13 +7,22 @@
   libsbuf,
   libutil,
   libxo,
-  pkg-config,
   mkAppleDerivation,
+  pkg-config,
+  pkgs,
 }:
 
 let
+  f =
+    pkgs: prev:
+    if !pkgs.stdenv.hostPlatform.isDarwin || pkgs.stdenv.name == "bootstrap-stage0-stdenv-darwin" then
+      prev.darwin.sourceRelease
+    else
+      f pkgs.stdenv.__bootPackages pkgs;
+  bootstrapSourceRelease = f pkgs pkgs;
+  # TODO(reckenrode): Use `sourceRelease` after migration has been merged and all releases updated to the same version.
   # nohup requires vproc_priv.h from launchd
-  launchd = apple-sdk.sourceRelease "launchd";
+  launchd = bootstrapSourceRelease "launchd";
 in
 mkAppleDerivation {
   releaseName = "shell_cmds";