Auto-detect minor version number for partial updates am: dc4b670837 am: b257ab6d5e am: d37cea46e4

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2734255

Change-Id: I0c15c86a42bc6651b3b56354de74593e6ef03daf
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>