refine needs to match packages back to roots, and it gets confused if
the same root appears twice. Deduplicate roots the same way we
deduplicate packages.
Introduce a new wrapper around driverResponse to make this easier, and
pass that around instead of the addPackage callback.
Fixesgolang/go#29297
Change-Id: I49ea37155c507af136391b9eb55a83b6dedfcc14
Reviewed-on: https://go-review.googlesource.com/c/155020
Run-TryBot: Heschi Kreinick <heschi@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>