Skip merge_operations which are not SOURCE_COPY am: 59724d8ad0 am: b8e2485b17

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/1581809

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I14a4654f692d0eba6b9fd96aa374f1bcf9eb44e6