anchor.diff:  { stdenv
   , lib
   , fetchFromGitHub
  +, applyPatches
   , bundlerEnv
   , defaultGemConfig
   , callPackage
  
positive.code: 
    src = sourceDir;
  
    patches = [
      ./0001-nulldb.patch
    ];
  
    buildInputs = [
      rubyEnv
      rubyEnv.wrappedRuby
  
negative.code:   pname = "zammad";
    version = "5.0.2";
  
    sourceDir = applyPatches "zammad-patched" {
  
      src = fetchFromGitHub (builtins.fromJSON (builtins.readFile ./source.json));
  
      patches = [ ./0001-nulldb.patch ];
  
      postPatch = ''
        sed -i -e "s|ruby '2.7.4'|ruby '${ruby_2_7.version}'|" Gemfile
        sed -i -e "s|ruby 2.7.4p191|ruby ${ruby_2_7.version}|" Gemfile.lock
        sed -i -e "s|2.7.4|${ruby_2_7.version}|" .ruby-version
      '';
    };
  
    databaseConfig = writeText "database.yml" ''
      production:
  