lemmy-ui: fix asset URLs

As `fetchFromGitHub` does not preserve the `.git` directory,
lemmy-ui fails to derive the value for its `COMMIT_HASH` variable
during the build.
The package previously (and mistakenly) assumed that `src.rev`
would somehow return the commit hash and not the version.
Fortunately, we do not need to know the precise commit rev.
This value is only used to generate the templated URLs without
further processing (and is also only injected for cache invalidation).

nixos/modules/services/web-apps/lemmy.nix

@@ -210,7 +210,7 @@ in
               root * ${cfg.ui.package}/dist
               file_server
             }
-            handle_path /static/${cfg.ui.package.passthru.commit_sha}/* {
+            handle_path /static/${cfg.ui.package.version}/* {
               root * ${cfg.ui.package}/dist
               file_server
             }

pkgs/servers/web-apps/lemmy/ui.nix

@@ -18,15 +18,13 @@ stdenvNoCC.mkDerivation (finalAttrs: {
   pname = "lemmy-ui";
   version = pinData.uiVersion;
 
-  src =
-    with finalAttrs;
-    fetchFromGitHub {
-      owner = "LemmyNet";
-      repo = "lemmy-ui";
-      rev = version;
-      fetchSubmodules = true;
-      hash = pinData.uiHash;
-    };
+  src = fetchFromGitHub {
+    owner = "LemmyNet";
+    repo = "lemmy-ui";
+    tag = finalAttrs.version;
+    fetchSubmodules = true;
+    hash = pinData.uiHash;
+  };
 
   nativeBuildInputs = [
     nodejs
@@ -48,20 +46,17 @@ stdenvNoCC.mkDerivation (finalAttrs: {
   buildPhase = ''
     runHook preBuild
 
-    pnpm build:prod
+    pnpm run prebuild:prod
+    # Required to pass a custom value for COMMIT_HASH, as the normal
+    # `pnpm build:prod` tries to derive its value by running `git`.
+    # This value is only injected into the templated asset URLs for cache invalidation,
+    # so we don't really need a commit hash here, just a value that changes on every
+    # update.
+    pnpm exec webpack --env COMMIT_HASH="${finalAttrs.version}" --mode=production
 
     runHook postBuild
   '';
 
-  # installPhase = ''
-  #     runHook preInstall
-
-  #     mkdir -p $out/{bin,lib/${finalAttrs.pname}}
-  #     mv {dist,node_modules} $out/lib/${finalAttrs.pname}
-
-  #     runHook postInstall
-
-  #  '';
   preInstall = ''
     mkdir $out
     cp -R ./dist $out
@@ -81,7 +76,6 @@ stdenvNoCC.mkDerivation (finalAttrs: {
   passthru = {
     updateScript = ./update.py;
     tests.lemmy-ui = nixosTests.lemmy;
-    commit_sha = finalAttrs.src.rev;
   };
 
   meta = {