Change rietveld.py to use GET on get_depends_on_patchset
Change rietveld.py to use GET on get_depends_on_patchset

Bug: 770327
Change-Id: I9dd0ed0be0761de4968136f563e8986b979c35cf
Reviewed-on: https://chromium-review.googlesource.com/723824
Commit-Queue: Aaron Gable <bbed39beedae4cdb499af742d2fcd6c63934d93b@chromium.org>
Reviewed-by: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@chromium.org>

CoherentLabs/depot_tools,CoherentLabs/depot_tools