anchor.diff:          }
         ]
   
  -      ++ optional config.nix.distributedBuilds
  +      ++ optional (config.nix.distributedBuilds && !config.nix.manualNixMachines)
           { # List of machines for distributed Nix builds in the format expected
             # by build-remote.pl.
             source = pkgs.writeText "nix.machines"
  
positive.code:         description = "
            Whether to distribute builds to the machines listed in
            <option>nix.buildMachines</option>.
          ";
        };
  
  
negative.code:           ''
              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} \
  