anchor.diff:  { stdenv, fetchurl, autoconf, automake, makeWrapper
  -, python, perl, perlPackages
  +, python3, perl, perlPackages
   , libmd, gnupg1, which, getopt, libpaper, nettools, qprint
   , sendmailPath ? "/run/wrappers/bin/sendmail" }:
   
   let
     # All runtime dependencies from the CPAN graph:
     # https://widgets.stratopan.com/wheel?q=GnuPG-Interface-0.52&runtime=1&fs=1
  -  # TODO: XSLoader seems optional
     GnuPGInterfaceRuntimeDependencies = with perlPackages; [
       strictures ClassMethodModifiers DataPerl DevelGlobalDestruction ExporterTiny
       GnuPGInterface ListMoreUtils ModuleRuntime Moo MooXHandlesVia MooXlate
  
positive.code:   ];
  in stdenv.mkDerivation rec {
    pname = "signing-party";
    version = "2.7";
    name = "${pname}-${version}";
  
    src = fetchurl {
      url = "mirror://debian/pool/main/s/${pname}/${pname}_${version}.orig.tar.gz";
      sha256 = "0znklgvxn7k7p6q7r8chcj86zmzildjamr3qlqfxkj5m7yziqr21";
    };
  
    sourceRoot = ".";
  
    # TODO: Get this patch upstream...
    patches = [ ./gpgwrap_makefile.patch ];
  
negative.code:   # Perl is required for it's pod2man.
    # Python and Perl are required for patching the script interpreter paths.
    nativeBuildInputs = [ autoconf automake makeWrapper ];
    buildInputs = [ python3 perl perlPackages.GnuPGInterface libmd gnupg1 ];
  
    postInstall = ''
      # Install all tools which aren't handled by 'make install'.
  