internal/worker: ignore std in fetchAndUpdateRawLatest

Change-Id: Ie16a08c1cac429532db7c6b1e76b75b540b6b0a0
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/296949
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
diff --git a/internal/worker/fetch.go b/internal/worker/fetch.go
index e89b0a5..46b5105 100644
--- a/internal/worker/fetch.go
+++ b/internal/worker/fetch.go
@@ -399,6 +399,9 @@
 // and updates the database if the version has changed.
 func (f *Fetcher) fetchAndUpdateRawLatest(ctx context.Context, modulePath string) (err error) {
 	defer derrors.Wrap(&err, "fetchAndUpdateRawLatest(%q)", modulePath)
+	if modulePath == stdlib.ModulePath {
+		return nil
+	}
 	info, err := fetch.RawLatestInfo(ctx, modulePath, f.ProxyClient, func(v string) (bool, error) {
 		modinfo, err := f.DB.GetModuleInfo(ctx, modulePath, v)
 		if err != nil {