The extra build can't be required, because it is not run for the
build of the first GOARCH later in the loop. Tests run fine
without it.
Change-Id: Ida27e31ace2417192cce06c2efc93fa0d357012e
Reviewed-on: https://go-review.googlesource.com/98975
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>