Closing commits in merge request don't mark corresponding issues

Summary

Creating a commit that closes an issue (i.e. message contains "fixes #xxx") then creating a merge request with that commit does not add that PR to the list of "Related merge requests" for that issue.

Steps to reproduce

1. Create a new issue (#xxx)
2. Create a new branch
3. Push a commit to that branch that will close the issue opened in step 1 (i.e. "fixes #xxx")
4. Create a new merge request for that branch (!yyy)
5. The merge request will say that it closes #xxx, but the issue does not have !yyy listed under the list of related merge requests

Example Project

Project, Merge Request, Issue

What is the current bug behavior?

The issue (#xxx) does not have !yyy listed under the list of related merge requests.

What is the expected correct behavior?

The issue (#xxx) should have !yyy listed under the list of related merge requests.

Relevant logs and/or screenshots

N/A, see linked project for live example.

Output of checks

This bug happens on GitLab.com, but was discovered on a self-hosted GitLab server.

Results of GitLab environment info

I do not have access to run this command.

Results of GitLab application Check

I do not have access to run this command.

Possible fixes

I have not yet searched for possible fixes.