anchor.diff:            ''
               export PATH=${if config.nix.distributedBuilds then "${pkgs.openssh}/bin:${pkgs.gzip}/bin:" else ""}${pkgs.openssl}/bin:${nix}/bin:$PATH
               ${config.nix.envVars}
  +            # To reduce the load on Hydra, don't start all those
  +            # unnecessary substituter processes.
  +            export NIX_SUBSTITUTERS=
               exec \
                 nice -n ${builtins.toString config.nix.daemonNiceLevel} \
                 ${pkgs.utillinux}/bin/ionice -n ${builtins.toString config.nix.daemonIONiceLevel} \
  
positive.code:         }
        ]
  
        ++ optional config.nix.distributedBuilds
          { # List of machines for distributed Nix builds in the format expected
            # by build-remote.pl.
            source = pkgs.writeText "nix.machines"
  
negative.code:         description = "
            Whether to distribute builds to the machines listed in
            <option>nix.buildMachines</option>.
          ";
        };
  
        manualNixMachines = mkOption {
          default = false;
          description = "
            Whether to manually manage the list of buildmachines used in distributed 
            builds in /etc/nix.machines. 
          ";
        };
  
  