Fixes golang/go#61417

Change-Id: Ib8599f39b4839bf6eed021217350195ad36d1631
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/605955
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>