Fixes #14613

Change-Id: I40d9696db3879549e78373ef17f6c92bd4b3470b
Reviewed-on: https://go-review.googlesource.com/21596Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-on: https://go-review.googlesource.com/22051
Run-TryBot: Andrew Gerrand <adg@golang.org>