anchor.diff:      postMount ? "",
       postUmount ? ""
     }:
  -    vmTools.runInLinuxVM (
  +  let
  +    result = vmTools.runInLinuxVM (
         runCommand name {
           preVM = vmTools.createEmptyImage {
             size = diskSize;
  
positive.code:           # originally this used `sed -i "1i$layerID" layer-list`, but
            # would fail if layer-list was completely empty.
            echo "$layerID/layer.tar"
          ) | ${pkgs.moreutils}/bin/sponge layer-list
  
          # Create image json and image manifest
          imageJson=$(cat ${baseJson} | jq ". + {\"rootfs\": {\"diff_ids\": [], \"type\": \"layers\"}}")
  
negative.code:       inherit imageDigest;
        imageName = finalImageName;
        imageTag = finalImageTag;
        impureEnvVars = stdenv.lib.fetchers.proxyImpureEnvVars;
        outputHashMode = "flat";
        outputHashAlgo = "sha256";
        outputHash = sha256;
  
        nativeBuildInputs = lib.singleton skopeo;
        SSL_CERT_FILE = "${cacert.out}/etc/ssl/certs/ca-bundle.crt";
  
        sourceURL = "docker://${imageName}@${imageDigest}";
        destNameTag = "${finalImageName}:${finalImageTag}";
  