Merge request patches cannot be downloaded

Summary

Merge requests patches cannot be accessed.

Steps to reproduce

Go to a merge request, verify it is accessible:

weitzman/drupal-test-traits!47 (merged)

Go to the patch link, and verify it is inaccessible:

https://gitlab.com/weitzman/drupal-test-traits/merge_requests/47.patch

Example Project

https://gitlab.com/weitzman/drupal-test-traits/merge_requests

What is the current bug behavior?

There is a 500 error response.

What is the expected correct behavior?

There is a patch file.