File Permissions changes aren't shown on Merge Requests

Summary

Merge Requests don't show permissions changes on files on GitLab EE

Steps to reproduce

1. Create a change to a project which changes a file's permissions (e.g. change a file from 0644 to 0777) and commit it to a branch.

2. View the single commit in GitLab {project}/commit/{sha_hash}

3. Observe the file permissions being changed.

4. Open a merge request for that branch.

5. Observe that the merge request at {project}/merge_requests/{id]/diffs doesn't show the permissions change.

This means that code reviewers don't see the permissions change unless they individually browse through the commits.

Note, viewing a single commit in the merge request still isn't sufficient.

What is the current bug behavior?

File permissions changes aren't visible on MRs meaning MRs merge changes containing permissions changes erroneously.

What is the expected correct behavior?

File permissions changes are visible, and the changes are seen by the reviewer.