Check for metadata hash if specified am: abb082f499 am: 4c5cdb44f5

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2568976

Change-Id: I8c7b6c7df37553edd97c65ce49eadffe7af647b3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>