Fixes #19478

Change-Id: I9fc186610d79fd003e7b5d88c0955286ebe7d3cf
Reviewed-on: https://go-review.googlesource.com/38634Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>