Merge commit SHA not showing in merge request widget

Summary

When a merge request is merged, a merge commit is created and the SHA shown in the merge request widget.

Steps to reproduce

Not sure, visit gitlab-org/gitlab-ce!22193 and you will see that the link to the commit is missing. Looking at gitlab-org/gitlab-ce!22030 it seems to have the SHA as expected.

Only difference I see is that gitlab-org/gitlab-ce!22193 still has the source branch available.

Example Project

gitlab-org/gitlab-ce!22193

What is the current bug behavior?

Commit link is not shown, but the user still can copy the copy SHA button

What is the expected correct behavior?

Show SHA link.

Relevant logs and/or screenshots

Screen_Shot_2018-10-09_at_16.33.41

Output of checks

This bug happens on GitLab.com