Automatic merge from submit-queue

Docker digest validation is too strict

Docker 1.10 does not guarantee that the pulled digest matches the digest
on disk when dealing with v1 schemas stored in a Docker registry. This
is the case for images like
centos/ruby-23-centos7@sha256:940584acbbfb0347272112d2eb95574625c0c60b4e2fdadb139de5859cf754bf
which as a result of #30366 cannot be pulled by Kube from a Docker 1.10
system.

This partially reverts commit 875fd16e.