Fixes #14072.

Change-Id: Ie31caa06690ac621906fc5acd34da2efa4e2049f
Reviewed-on: https://go-review.googlesource.com/18860Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>