Commit email notifications don't contain a diff for large files

Summary

Commit email notifications don't contain a diff for small changes to large files

Steps to reproduce

  • Have a repository with a very large (e.g. 15MB) plain text file
  • Subscribe to push email notifications
  • Make a small change, e.g. a one line change
  • Receive a push notification email
  • The email contains something like: "No preview for this file type"

Example Project

https://gitlab.com/pochu/security-tracker

Affected file: https://gitlab.com/pochu/security-tracker/blob/master/data/CVE/list

Example commit: https://gitlab.com/pochu/security-tracker/commit/e2f209f8a0e67e70e5e71646b4ffb550aae7c728

Note that this commit shows a diff on the web, so I would expect an email notification to contain a diff as well

What is the current bug behavior?

Email notifications contain:

1 changed file:

data/CVE/list

Changes: data/CVE/list No preview for this file type

What is the expected correct behavior?

A code diff should be shown, just like on the web

Relevant logs and/or screenshots

See email Message-ID: 5a6af40f37359_15d2c3fe935fd84b016286389@sidekiq-asap-03.mail

Also see attached screenshot. gitlab-email

Output of checks

This bug happens on GitLab.com