This makes them accessible to presubmit scripts' PostUploadHook.

Fixed bugs where caching needed to be bypassed in order for
sequential PostUploadHooks to see each others' results.

BUG=688765

Change-Id: I56c0c6b6419e2474f4b7f701be036fb2a524f8e3
Reviewed-on: https://chromium-review.googlesource.com/439877Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Paweł Hajdan Jr. <phajdan.jr@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>