Fixes #28234

Change-Id: I89090ffb8285c4936b0c9b5c2475849c0643186a
GitHub-Last-Rev: 4dd0ec162d0ce1548045d4119fd3295570f65d85
GitHub-Pull-Request: golang/go#28246
Reviewed-on: https://go-review.googlesource.com/c/142877Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>