Empty state is wrong when comparing merge request versions

Steps to reproduce

  • push an empty commit to a merge request or squash existing commits
  • click Compare with previous version on discussion tab

Example Project

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28216/diffs?diff_id=41550743&start_sha=b532c55778e4d42654431bbc4dc8dbda134b26c2

What is the current bug behavior?

The top of the changes tab mentions Changes between latest version and version ... but the empty state claims No changes between ... and master (which is wrong):

wrong-empty-state

What is the expected correct behavior?

Display No changes between latest version and version ... in the empty state.