anchor.diff:  
     preConfigure = ''
       mesonFlagsArray+=(-Dntp-servers="0.nixos.pool.ntp.org 1.nixos.pool.ntp.org 2.nixos.pool.ntp.org 3.nixos.pool.ntp.org")
  -    mesonFlagsArray+=(-Ddbuspolicydir=$out/etc/dbus-1/system.d)
  -    mesonFlagsArray+=(-Ddbussessionservicedir=$out/share/dbus-1/services)
  -    mesonFlagsArray+=(-Ddbussystemservicedir=$out/share/dbus-1/system-services)
  -    mesonFlagsArray+=(-Dpamconfdir=$out/etc/pam.d)
  -    mesonFlagsArray+=(-Drootprefix=$out)
  -    mesonFlagsArray+=(-Drootlibdir=$lib/lib)
  -    mesonFlagsArray+=(-Dpkgconfiglibdir=$dev/lib/pkgconfig)
  -    mesonFlagsArray+=(-Dpkgconfigdatadir=$dev/share/pkgconfig)
  -
       export LC_ALL="en_US.UTF-8";
       # FIXME: patch this in systemd properly (and send upstream).
       # already fixed in f00929ad622c978f8ad83590a15a765b4beecac9: (u)mount
  
positive.code: , withKexectools ? lib.any (lib.meta.platformMatch stdenv.hostPlatform) kexectools.meta.platforms, kexectools
  }:
  
  let
    pythonLxmlEnv = buildPackages.python3Packages.python.withPackages ( ps: with ps; [ python3Packages.lxml ]);
  
  in stdenv.mkDerivation rec {
    version = "239.20190219";
    name = "systemd-${version}";
  
    # When updating, use https://github.com/systemd/systemd-stable tree, not the development one!
  
negative.code:       stdenv.lib.optional withLibseccomp libseccomp ++
      [ libffi audit lz4 bzip2 libapparmor
        iptables gnu-efi
      ] ++ stdenv.lib.optional withSelinux libselinux;
  
    #dontAddPrefix = true;
  
    mesonFlags = [
      "-Ddbuspolicydir=${placeholder "out"}/etc/dbus-1/system.d"
      "-Ddbussessionservicedir=${placeholder "out"}/share/dbus-1/services"
      "-Ddbussystemservicedir=${placeholder "out"}/share/dbus-1/system-services"
      "-Dpamconfdir=${placeholder "out"}/etc/pam.d"
      "-Drootprefix=${placeholder "out"}"
      "-Drootlibdir=${placeholder "lib"}/lib"
      "-Dpkgconfiglibdir=${placeholder "dev"}/lib/pkgconfig"
      "-Dpkgconfigdatadir=${placeholder "dev"}/share/pkgconfig"
      "-Dloadkeys-path=${kbd}/bin/loadkeys"
      "-Dsetfont-path=${kbd}/bin/setfont"
      "-Dtty-gid=3" # tty in NixOS has gid 3
  