This was pointed out in https://go-review.googlesource.com/#/c/27315/1
but I changed and uploaded the wrong branch. This actually makes the
fix.

Change-Id: Ib615b06c9141b914648b6abbeeb688c5ffa0d2e3
Reviewed-on: https://go-review.googlesource.com/27360Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>