anchor.diff:      sha256 = "1ddwzg12pbzpnz3njin4zhpph92kscrbsn3bzds26yj8fp76zc33";
     };
   
  -  containers = mkContrib "containers" [ "8.6" "8.7" "8.8" ] {
  +  containers = mkContrib "containers" [ "8.6" "8.7" "8.8" "8.9" ] {
       "8.6" = {
         version = "8.6.0";
         rev = "fa1fec7";
  
positive.code: 
      buildInputs = with coq.ocamlPackages; [ ocaml camlp5 findlib coq ];
  
      installFlags = "COQLIB=$(out)/lib/coq/${coq.coq-version}/";
  
      passthru = {
        compatibleCoqVersions = v: builtins.elem v revs;
  
negative.code:       rev = "52b86bed1671321b25fe4d7495558f9f221b12aa";
        sha256 = "0hbnrwdgryr52170cfrlbiymr88jsyxilnpr343vnprqq3zk1xz0";
      };
      "8.9" = {
        version = "20190222";
        rev = "aa33052c1edfc5a65885942a67c2773b5d96f8cc";
        sha256 = "0mjgfdr9bzsch0dlk4vq1frkaig14dqh46r54cv0l15flxapg0iw";
      };
    }."${coq.coq-version}";
  
    continuations = mkContrib "continuations" [ ] {
  