Related merge requests not found in squashed Commit

Summary

Related merge requests miss in a Commit page with the squashed commit in MR approvals.

Steps to reproduce

1. Access to https://gitlab.com/gitlab-org/gitlab-ce/commit/81bdb6ad8a39b7b9645bcfb4178a14a11f5de9e1 to find it missing !16573 (merged) these (alternatively seeing No related merge requests found)

What is the current bug behavior?

We can't see related MRs on the squashed commit generated on the MR.

What is the expected correct behavior?

We should see related MRs even in the squashed commit on the MR.

Relevant logs and/or screenshots

(Paste any relevant logs - please use code blocks (```) to format console output, logs, and code as it's very hard to read otherwise.)

Output of checks

This bug happens on GitLab.com (11.4.2-ee).