anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "google-compute-engine-oslogin";
  -  version = "1.5.3";
  -  # from packages/google-compute-engine-oslogin/packaging/debian/changelog
  +  version = "20200325.00";
   
     src = fetchFromGitHub {
       owner = "GoogleCloudPlatform";
  -    repo = "compute-image-packages";
  -    rev = "20190522";
  -    sha256 = "16jbbrnz49g843h813r408dbvfa2hicf8canxwbfxr2kzhv7ycmm";
  +    repo = "guest-oslogin";
  +    rev = version;
  +    sha256 = "03hk95pgzcgy6ginp8zdy0fbk88m6n65qq22jq490z1xwbjffm8r";
     };
  -  sourceRoot = "source/packages/google-compute-engine-oslogin";
   
     postPatch = ''
       # change sudoers dir from /var/google-sudoers.d to /run/google-sudoers.d (managed through systemd-tmpfiles)
  -    substituteInPlace pam_module/pam_oslogin_admin.cc --replace /var/google-sudoers.d /run/google-sudoers.d
  +    substituteInPlace src/pam/pam_oslogin_admin.cc --replace /var/google-sudoers.d /run/google-sudoers.d
       # fix "User foo not allowed because shell /bin/bash does not exist"
  -    substituteInPlace compat.h --replace /bin/bash ${bashInteractive}/bin/bash
  +    substituteInPlace src/include/compat.h --replace /bin/bash ${bashInteractive}/bin/bash
     '';
   
     buildInputs = [ curl.dev pam ];
  
positive.code:   NIX_CFLAGS_COMPILE="-I${json_c.dev}/include/json-c";
    NIX_CFLAGS_LINK="-L${json_c}/lib";
  
    installPhase = ''
      mkdir -p $out/{bin,lib}
  
      install -Dm755 libnss_cache_google-compute-engine-oslogin-${version}.so $out/lib/libnss_cache_oslogin.so.2
      install -Dm755 libnss_google-compute-engine-oslogin-${version}.so $out/lib/libnss_oslogin.so.2
  
      install -Dm755 pam_oslogin_admin.so pam_oslogin_login.so $out/lib
      install -Dm755 google_{oslogin_nss_cache,authorized_keys} $out/bin
    '';
  
    enableParallelBuilding = true;
  
  
negative.code: { stdenv
  , lib
  , fetchFromGitHub
  , curl
  , json_c
  