nixos/etc-overlay: replace pkgs.move-mount-beneath with mount, move-mount-beneath: drop (#515304)

nixos/modules/system/etc/etc.nix

@@ -337,11 +337,7 @@ in
               done
 
               # Move the new temporary /etc mount underneath the current /etc mount.
-              #
-              # This should eventually use util-linux to perform this move beneath,
-              # however, this functionality is not yet in util-linux. See this
-              # tracking issue: https://github.com/util-linux/util-linux/issues/2604
-              ${pkgs.move-mount-beneath}/bin/move-mount --move --beneath "$tmpEtcMount" /etc
+              mount --move --beneath "$tmpEtcMount" /etc
 
               # Unmount the top /etc mount to atomically reveal the new mount.
               umount --lazy --recursive /etc

pkgs/by-name/mo/move-mount-beneath/package.nix

@@ -1,31 +0,0 @@
-{
-  lib,
-  stdenv,
-  fetchFromGitHub,
-}:
-
-stdenv.mkDerivation {
-  pname = "move-mount-beneath";
-  version = "0-unstable-2025-09-24";
-
-  src = fetchFromGitHub {
-    owner = "brauner";
-    repo = "move-mount-beneath";
-    rev = "f8773d1f99f9cfa2f5bf173e1b1d1b21eb1ee446";
-    hash = "sha256-C7QiClwFTKBcdmGilwZSCAsaVoEDXTO9384Y/47JrPk=";
-  };
-
-  installPhase = ''
-    runHook preInstall
-    install -D move-mount $out/bin/move-mount
-    runHook postInstall
-  '';
-
-  meta = {
-    description = "Toy binary to illustrate adding a mount beneath an existing mount";
-    mainProgram = "move-mount";
-    homepage = "https://github.com/brauner/move-mount-beneath";
-    license = lib.licenses.mit0;
-    maintainers = with lib.maintainers; [ nikstur ];
-  };
-}

pkgs/top-level/aliases.nix

@@ -1445,6 +1445,7 @@ mapAliases {
   moralerspace-hwnf = throw "moralerspace-hwnf has been removed, use moralerspace-hw instead."; # Added 2025-08-30
   moralerspace-nf = throw "moralerspace-nf has been removed, use moralerspace instead."; # Added 2025-08-30
   morty = throw "morty has been removed, as searxng removed support for it and it was unmaintained."; # Added 2025-09-26
+  move-mount-beneath = throw "move-mount-beneath has been removed, it is now superseded by util-linux's mount"; # Added 2026-05-19
   moz-phab = throw "'moz-phab' has been renamed to/replaced by 'mozphab'"; # Converted to throw 2025-10-27
   mp3splt = throw "'mp3splt' has been removed due to lack of maintenance upstream."; # Added 2025-05-17
   mpage = throw "'mpage' has been removed due to being unmaintained and broken"; # Added 2026-05-05