Fix multiarch image push in docker engine

[KavyaSree2610]

Merge Checklist

All boxes should be checked before merging the PR (just tick any boxes which don't apply to this PR)

• The toolchain has been rebuilt successfully (or no changes were made to it)
• The toolchain/worker package manifests are up-to-date
• Any updated packages successfully build (or no packages were changed)
• Packages depending on static components modified in this PR (Golang, *-static subpackages, etc.) have had their Release tag incremented.
• Package tests (%check section) have been verified with RUN_CHECK=y for existing SPEC files, or added to new SPEC files
• All package sources are available
• cgmanifest files are up-to-date and sorted (./cgmanifest.json, ./toolkit/scripts/toolchain/cgmanifest.json, .github/workflows/cgmanifest.json)
• LICENSE-MAP files are up-to-date (./LICENSES-AND-NOTICES/SPECS/data/licenses.json, ./LICENSES-AND-NOTICES/SPECS/LICENSES-MAP.md, ./LICENSES-AND-NOTICES/SPECS/LICENSE-EXCEPTIONS.PHOTON)
• All source files have up-to-date hashes in the *.signatures.json files
• sudo make go-tidy-all and sudo make go-test-coverage pass
• Documentation has been updated to match any changes to the build system
• Ready to merge

---

Summary

What does the PR accomplish, why was it needed?

ICM: https://portal.microsofticm.com/imp/v5/incidents/details/666786675/summary

This PR backports an upstream Docker fix to moby-engine 25.0.3 that resolves an Azure Container Registry geo-replication inconsistency issue.

The bug causes all image layers to be pushed with the same vars_reference value (the image tag) instead of unique layer digests. This leads to race conditions during concurrent pushes, resulting in last-writer-wins behavior and tag-to-digest mismatches across geo-replicated regions. Customers experience images being available in one region but missing or corrupted in others.

The fix ensures each layer is pushed with its unique SHA256 digest as the vars_reference, enabling reliable geo-replication across ACR regions.

Upstream reference: moby/moby#49949

Change Log

• Fix multiarch image push in docker engine

Does this affect the toolchain?

NO

Associated issues

• https://microsoft.visualstudio.com/OS/_workitems/edit/58935444/

Links to CVEs

• https://nvd.nist.gov/vuln/detail/CVE-YYYY-XXXX

Test Methodology

• Pipeline build:
  - Buddy build: https://dev.azure.com/mariner-org/mariner/_build/results?buildId=1066982&view=results
  - Full build id: 3.0.20260316-kkaitepalli-1070381 (successful)

[mfrw]

I think we should get a few more folks to take a look :)

[mfrw]

LGTM :)

[cpuguy83]

We merged the patch upstream in the v25 branch: moby/moby#52169
No ETA on a release date with the patch.

[KavyaSree2610]

PR check failing is not related

[kgodara912]

The patch matches with upstream version of patch and also the patch is merged for our current branch of moby-engine in upstream as well by the author. Buddy build is successful. The follow-ups in upstream patch are already verified by the author, and they are not required for the current version of moby-engine in Azure Linux. LGTM.