Number of files listed on merge request changes tab incorrect when truncated

Summary

When merge request changes are truncated the tab displays "nnn+ changes" but number of files is displayed is the number of files excluding those outside of the truncated changes. This is misleading for the user who sees different output to that of their git diff, causing them to doubt the integrity of the merge request.

The above should read "177 Files displayed", or "177+ Files".

Steps to reproduce

Create a merge request with a large number of files.

Example Project

Created a test project here: amulvany/support-issues!5 (diffs)

What is the current bug behavior?

Incorrect number of files displayed

What is the expected correct behavior?

Show total count of all files, or be explicit to the user.

Relevant logs and/or screenshots

Output of checks

(If you are reporting a bug on GitLab.com, write: This bug happens on GitLab.com)

Results of GitLab environment info

Results of GitLab application Check

Possible fixes

Could update https://gitlab.com/gitlab-org/gitlab/blob/master/app%2Fassets%2Fjavascripts%2Fdiffs%2Fcomponents%2Fdiff_stats.vue#L24 to return n__('File', 'Files', this.diffFilesLength + " displayed");

Customer has reported this issue: https://gitlab.zendesk.com/agent/tickets/134702 (Internal use only)