The test no longer passes as of https://golang.org/cl/43777, which
intentionally disables the feature that this test was checking for.
Nobody noticed since the test is not run in -short mode.

Updates #20435.

Change-Id: I64f37fd94c01f22ead88470b6d9bfe8a151ddb1c
Reviewed-on: https://go-review.googlesource.com/44650Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>