Merge "libsnapshot: Propagate merge phase across merge failures." am:...

Merge "libsnapshot: Propagate merge phase across merge failures." am: d32f5df7 am: 82d0ee6b am: 38d40238

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1770177

Change-Id: Ic3b156b03ae5d1b32d843d8cb8e629ced39b52a1