anchor.diff:  
   buildPerlPackage rec {
     pname = "public-inbox";
  -  version = "1.7.0";
  +  version = "unstable-2022-04-05";
   
     src = fetchurl {
  -    url = "https://public-inbox.org/public-inbox.git/snapshot/public-inbox-${version}.tar.gz";
  -    sha256 = "sha256-hQSpmAFFVuPmXZvc7q6yP5Zhl86oar83OLYFn+42yMk=";
  +    url = "https://public-inbox.org/public-inbox.git/snapshot/public-inbox-961690bae47c90a4a6960952587c6f4463fb4b19.tar.gz";
  +    sha256 = "sha256-dvo+0kCZZQlXudtWyv8Npf3KhSC8pg95CmP7fMFqgww=";
     };
   
     outputs = [ "out" "devdoc" "sa_config" ];
  
positive.code:   ];
    preCheck = ''
      perl certs/create-certs.perl
      export HOME="$NIX_BUILD_TOP"/home
      mkdir -p "$HOME"/.cache/public-inbox/inline-c
    '';
  
negative.code:     #   expected: anything else
      # waiting for child to reap grandchild...
      "spawn"
    ];
  
    testConditions = with lib;
  