Merge "Abandon other staged sessions when a rollback is staged." into sc-dev...

Merge "Abandon other staged sessions when a rollback is staged." into sc-dev am: 79bbe49b am: 4cf74719

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15132975

Change-Id: Id5fa41d08eb45296882faf36a213adeb3f477226