xdeltaUnstable: drop

xdeltaUnstable uses the same source as xdelta and is a leaf package.
Considering that xdelta hasn't received any update upstream in 9 years,
we probably don't need the extra `xdeltaUnstable` attr.

pkgs/tools/compression/xdelta/unstable.nix

@@ -1,69 +0,0 @@
-{
-  lib,
-  stdenv,
-  fetchFromGitHub,
-  autoreconfHook,
-  lzmaSupport ? true,
-  xz ? null,
-}:
-
-assert lzmaSupport -> xz != null;
-
-let
-  mkWith = flag: name: if flag then "--with-${name}" else "--without-${name}";
-in
-stdenv.mkDerivation rec {
-  pname = "xdelta";
-  version = "3.1.0";
-
-  src = fetchFromGitHub {
-    sha256 = "09mmsalc7dwlvgrda56s2k927rpl3a5dzfa88aslkqcjnr790wjy";
-    rev = "v${version}";
-    repo = "xdelta-devel";
-    owner = "jmacd";
-  };
-
-  nativeBuildInputs = [ autoreconfHook ];
-  buildInputs = [ ] ++ lib.optionals lzmaSupport [ xz ];
-
-  postPatch = ''
-    cd xdelta3
-
-    substituteInPlace Makefile.am --replace \
-      "common_CFLAGS =" \
-      "common_CFLAGS = -DXD3_USE_LARGESIZET=1"
-  '';
-
-  configureFlags = [
-    (mkWith lzmaSupport "liblzma")
-  ];
-
-  enableParallelBuilding = true;
-
-  doCheck = true;
-  checkPhase = ''
-    mkdir $PWD/tmp
-    for i in testing/file.h xdelta3-test.h; do
-      substituteInPlace $i --replace /tmp $PWD/tmp
-    done
-    ./xdelta3regtest
-  '';
-
-  installPhase = ''
-    install -D -m755 xdelta3 $out/bin/xdelta3
-    install -D -m644 xdelta3.1 $out/share/man/man1/xdelta3.1
-  '';
-
-  meta = {
-    description = "Binary differential compression in VCDIFF (RFC 3284) format";
-    longDescription = ''
-      xdelta is a command line program for delta encoding, which generates two
-      file differences. This is similar to diff and patch, but it is targeted
-      for binary files and does not generate human readable output.
-    '';
-    homepage = "http://xdelta.org/";
-    license = lib.licenses.gpl2Plus;
-    mainProgram = "xdelta3";
-    platforms = lib.platforms.linux;
-  };
-}

pkgs/top-level/aliases.nix

@@ -2026,6 +2026,7 @@ mapAliases {
   xcbutilrenderutil = libxcb-render-util; # Added 2026-02-04
   xcbutilwm = libxcb-wm; # Added 2026-02-04
   xcursorthemes = xcursor-themes; # Added 2026-01-19
+  xdeltaUnstable = throw "'xdeltaUnstable' has been replaced by 'xdelta'"; # Added 2026-02-17
   xdg-terminal-exec-mkhl = warnAlias "
     'xdg-terminal-exec-mkhl' has been removed due to being behind the xdg-terminal-exec spec for too long,
     use the reference implementation 'xdg-terminal-exec' instead.

pkgs/top-level/all-packages.nix

@@ -3679,8 +3679,6 @@ with pkgs;
   # It is also needed to reduce the amount of unnecessary stuff in the Darwin bootstrap.
   xarMinimal = callPackage ../by-name/xa/xar/package.nix { e2fsprogs = null; };
 
-  xdeltaUnstable = callPackage ../tools/compression/xdelta/unstable.nix { };
-
   xdot = with python3Packages; toPythonApplication xdot;
 
   libxfs = xfsprogs.dev;