This way you can still run 'go test' or 'go bench -run Foo'
without wondering why it is taking so very long.

Change-Id: Icfa097a6deb1d6682acb7be9f34729215c29eabb
Reviewed-on: https://go-review.googlesource.com/30707Reviewed-by: Robert Griesemer <gri@golang.org>