nixos-rebuild-ng: drop withReexec option

Different from `nixos-rebuild`, re-exec in `nixos-rebuild` should always
work, so there shouldn't be much of an issue enabling it by default.

nixos/modules/installer/tools/tools.nix

@@ -70,7 +70,6 @@ let
   nixos-install = pkgs.nixos-install.override { };
   nixos-rebuild-ng = pkgs.nixos-rebuild-ng.override {
     nix = config.nix.package;
-    withReexec = true;
   };
 
   defaultFlakeTemplate = ''

nixos/tests/installer.nix

@@ -726,9 +726,7 @@ let
                   libxml2.bin
                   libxslt.bin
                   nixos-artwork.wallpapers.simple-dark-gray-bottom
-                  (nixos-rebuild-ng.override {
-                    withReexec = true;
-                  })
+                  nixos-rebuild-ng
                   ntp
                   perlPackages.ConfigIniFiles
                   perlPackages.FileSlurp

pkgs/by-name/ni/nixos-rebuild-ng/package.nix

@@ -9,14 +9,12 @@
   python3Packages,
   runCommand,
   scdoc,
-  withReexec ? false,
   withShellFiles ? true,
   # Very long tmp dirs lead to "too long for Unix domain socket"
   # SSH ControlPath errors. Especially macOS sets long TMPDIR paths.
   withTmpdir ? if stdenv.hostPlatform.isDarwin then "/tmp" else null,
   # passthru.tests
   nixosTests,
-  nixos-rebuild-ng,
 }:
 let
   executable = "nixos-rebuild";
@@ -52,7 +50,6 @@ python3Packages.buildPythonApplication rec {
   postPatch = ''
     substituteInPlace nixos_rebuild/constants.py \
       --subst-var-by executable ${executable} \
-      --subst-var-by withReexec ${lib.boolToString withReexec} \
       --subst-var-by withShellFiles ${lib.boolToString withShellFiles}
   '';
 
@@ -97,10 +94,6 @@ python3Packages.buildPythonApplication rec {
       };
 
       tests = {
-        with_reexec = nixos-rebuild-ng.override {
-          withReexec = true;
-        };
-
         inherit (nixosTests)
           # FIXME: this test is disabled since it times out in @ofborg
           # nixos-rebuild-install-bootloader-ng

pkgs/by-name/ni/nixos-rebuild-ng/src/nixos_rebuild/__init__.py

@@ -5,7 +5,7 @@ from subprocess import CalledProcessError, run
 from typing import Final, assert_never
 
 from . import nix, services
-from .constants import EXECUTABLE, WITH_REEXEC, WITH_SHELL_FILES
+from .constants import EXECUTABLE, WITH_SHELL_FILES
 from .models import Action, BuildAttr, Flake, GroupedNixArgs, Profile
 from .process import Remote
 from .utils import LogFormatter
@@ -288,7 +288,7 @@ def execute(argv: list[str]) -> None:
 
     # Re-exec to a newer version of the script before building to ensure we get
     # the latest fixes
-    if WITH_REEXEC and can_run and not args.no_reexec:
+    if can_run and not args.no_reexec:
         services.reexec(argv, args, grouped_nix_args)
 
     profile = Profile.from_arg(args.profile_name)

pkgs/by-name/ni/nixos-rebuild-ng/src/nixos_rebuild/constants.py

@@ -7,5 +7,4 @@ from typing import Final
 EXECUTABLE: Final[str] = "@executable@"
 # Use either `== "true"` if the default (e.g.: `python -m nixos_rebuild`) is
 # `False` or `!= "false"` if the default is `True`
-WITH_REEXEC: Final[bool] = "@withReexec@" == "true"
 WITH_SHELL_FILES: Final[bool] = "@withShellFiles@" == "true"