$ git merge -s ours origin/mainline-prod

There are only two commits not from upstream:
05cdb9972ac11770ab155b8b8e7fe61fcc168011
1be2664406a2e697044f483a44c547973f915e3d

But both of these are noops in master (due to Merged-In).

Bug: 168176832
Test: presubmit
Change-Id: Ic61fc2939b03615e152c37fd762dbcd81546f705