I would like to re-apply reverted http://golang.org/cl/8523.
Reverted tests still fail in some environments (see issue #10360).
It is easier to run tests selectively when in Go.
This CL prepares for the changes.

Updates #10360

Change-Id: Iefeb1d71cb3d1cfa653a6ccd9f6e35686c0c5b24
Reviewed-on: https://go-review.googlesource.com/10608Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>