Fix loading of Starlark aspects in builtins.

PiperOrigin-RevId: 375664574
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java
index aead10e..62b456b 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java
@@ -155,7 +155,10 @@
   static StarlarkAspect loadStarlarkAspect(
       Environment env, Label extensionLabel, String starlarkValueName)
       throws AspectCreationException, InterruptedException {
-    SkyKey importFileKey = BzlLoadValue.keyForBuild(extensionLabel);
+    SkyKey importFileKey =
+        StarlarkBuiltinsValue.isBuiltinsRepo(extensionLabel.getRepository())
+            ? BzlLoadValue.keyForBuiltins(extensionLabel)
+            : BzlLoadValue.keyForBuild(extensionLabel);
     try {
       BzlLoadValue bzlLoadValue =
           (BzlLoadValue) env.getValueOrThrow(importFileKey, BzlLoadFailedException.class);