Updates #18089.

Test for that issue; it was inadvertently fixed
by CL 34988. Ensure that we don't regress on the fix.

Change-Id: Icb85fc20dbb0a47f028f088281319b552b16759d
Reviewed-on: https://go-review.googlesource.com/42173Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>