The way it is done is by switching to a multiple phases model:
- Gather data
- Calculate actions
- Execute

Rolling multiple dependencies simultaneously is occasionally needed.
This will permit to supersede roll-deps.py in infra.git.

R=agable@chromium.org
Bug:
Change-Id: Ibdc7883268b2b08c8a0db1637a9601ffce943c48
Reviewed-on: https://chromium-review.googlesource.com/817616Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Marc-Antoine Ruel <maruel@chromium.org>