Fixes #14238

Change-Id: I1538bfb5cfa63e36a89df1f6eb9f5a0dcafb6ce5
Reviewed-on: https://go-review.googlesource.com/23256Reviewed-by: Dave Cheney <dave@cheney.net>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>