vimUtils: don't copy the build directory with dontUnpack (#568289)

pkgs/applications/editors/vim/plugins/utils/build-vim-plugin.nix

@@ -43,7 +43,7 @@
 
             target=$out/${rtpPath}/${path}
             mkdir -p $out/${rtpPath}
-            cp -r . $target
+            ${lib.optionalString (!(attrs.dontUnpack or false)) "cp -r . $target"}
 
             runHook postInstall
           '';

pkgs/test/vim/default.nix

@@ -25,6 +25,26 @@ lib.recurseIntoAttrs {
     vimrcConfig.packages.myVimPackage.start = with vimPlugins; [ vim-nix ];
   };
 
+  test_vim_plugin_dont_unpack =
+    let
+      plugin = vimUtils.buildVimPlugin {
+        pname = "vim-plugin-dont-unpack-test";
+        version = "0";
+        src = pkgs.writeText "probe.vim" "";
+        dontUnpack = true;
+        buildPhase = ''
+          install -D "$src" "$out/colors/probe.vim"
+        '';
+      };
+    in
+    pkgs.runCommand "vim-plugin-dont-unpack-test" { } ''
+      test -f ${plugin}/colors/probe.vim
+      for file in env-vars .attrs.json .attrs.sh; do
+        test ! -e ${plugin}/"$file"
+      done
+      mkdir -p "$out"
+    '';
+
   # test that all vimPlugins have `passthru.vimPlugin = true`
   test-all-plugins-have-vimPlugin-true =
     let