anchor.diff: -{ lib, stdenv, fetchFromGitHub, fetchpatch
  +{ lib, stdenv, fetchFromGitHub
   , autoreconfHook269, util-linux, nukeReferences, coreutils
   , perl, buildPackages
   , configFile ? "all"
  
positive.code:     # incompatibleKernelVersion = "4.20";
  
      # this package should point to the latest release.
      version = "2.0.1";
  
      sha256 = "0wmw823ildwm9rcfyk22pvzg100yhps3y9hfjlrpspfd1hhkbp0d";
  
      extraPatches = [ reapplyPathSanitizerPatch ];
    };
  
    zfsUnstable = common {
  
negative.code: let
    buildKernel = any (n: n == configFile) [ "kernel" "all" ];
    buildUser = any (n: n == configFile) [ "user" "all" ];
  
    common = { version
      , sha256
  