nixos-rebuild-ng: re-exec in the current version if re-exec to a new one fails (#366271)

            build_attr = BuildAttr.from_arg(args.attr, args.file)

            drv = nix.build(attr, build_attr, **build_flags, no_out_link=True)

    except CalledProcessError:

        logger.warning("could not build a newer version of nixos-rebuild")

        logger.warning(

            "could not build a newer version of nixos-rebuild, "

            + "using current version"

        )

    if drv:

        new = drv / f"bin/{EXECUTABLE}"

        if new != current:

            logging.debug(

                "detected newer version of script, re-exec'ing, current=%s, new=%s",

                argv[0],

                current,

                new,

            )

            # Manually call clean-up functions since os.execve() will replace

            # the process immediately

            cleanup_ssh()

            tmpdir.TMPDIR.cleanup()

            try:

                os.execve(new, argv, os.environ | {"_NIXOS_REBUILD_REEXEC": "1"})

            except Exception:

                # Possible errors that we can have here:

                # - Missing the binary

                # - Exec format error (e.g.: another OS/CPU arch)

                logger.warning(

                    "could not re-exec in a newer version of nixos-rebuild, "

                    + "using current version"

                )

                logger.debug("re-exec exception", exc_info=True)

                # We already run clean-up, let's re-exec in the current version

                # to avoid issues

                os.execve(current, argv, os.environ | {"_NIXOS_REBUILD_REEXEC": "1"})

def execute(argv: list[str]) -> None: