Fixes #17560

Change-Id: I96fcdec87220391ef5432571b5c090b5be27491a
Reviewed-on: https://go-review.googlesource.com/31771Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>