HttpsMethod::Fetch(): Zero the FetchResult object when leaving due to 404

methods/https.cc

@@ -402,6 +402,8 @@ bool HttpsMethod::Fetch(FetchItem *Itm)
       _error->Error("%s", err);
       // unlink, no need keep 401/404 page content in partial/
       unlink(File->Name().c_str());
+      Res.Size = 0;
+      Res.LastModified = 0;
       return false;
    }