Fixes #22238

Change-Id: I8184f789bd4120f3e71c9374c7c2fcbfa95935bf
Reviewed-on: https://go-review.googlesource.com/132635Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>