anchor.diff:    # (requiring it to be frequently rebuilt), which can be an
     # annoyance.
     callPackageKeepDeriver = src: args:
  -    overrideCabal (self.callPackage src args) (orig: {
  +    overrideCabal (orig: {
         preConfigure = ''
           # Generated from ${src}
           ${orig.preConfigure or ""}
  
positive.code:                   then pkgs.lib.cleanSourceWith { inherit src filter; }
                  else src;
          };
        in overrideCabal (callPackageKeepDeriver expr args) (orig: {
             inherit src;
           });
  
      callCabal2nix = name: src: args: self.callCabal2nixWithOptions name src "" args;
  
  
negative.code:         # cabal2nixDeriver field.
          cabal2nixDeriver = src;
        };
      }) (self.callPackage src args);
  
  in package-set { inherit pkgs lib callPackage; } self // {
  
  