cabal2nix: fix (and clean up)override for hpack dependency

pkgs/development/haskell-modules/hackage-packages.nix

@@ -41611,6 +41611,10 @@ self: {
          base Cabal containers directory filepath language-nix lens pretty
          process tasty tasty-golden
        ];
+       preCheck = ''
+         export PATH="$PWD/dist/build/cabal2nix:$PATH"
+         export HOME="$TMPDIR/home"
+       '';
        description = "Convert Cabal files into Nix build instructions";
        license = stdenv.lib.licenses.bsd3;
        maintainers = with stdenv.lib.maintainers; [ peti ];
@@ -202873,7 +202877,6 @@ self: {
        ];
        description = "Terminal emulator configurable in Haskell";
        license = stdenv.lib.licenses.bsd3;
-       hydraPlatforms = stdenv.lib.platforms.none;
      }) {gtk3 = pkgs.gnome3.gtk;};
 
   "termplot" = callPackage