Fix rollback detection am: 1bcd7d700c am: c6b0915022

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2439694

Change-Id: Ic59e0c386194ccf19c0fe1291d47be2931ed6573
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>