Can't reopen merged Merge Request: cannot transition via "reopen"

Summary

When I merge a Merge Request, and want to Reopen it, I can't

Steps to reproduce

1. Create a Merge Request
2. Merge It
3. Click "Reopen merge request"

Example Project

francovp/cant-reopen-merge-request-example!1 (merged)

What is the current bug behavior?

When you try to reopen a merged Merge Request you can't because it shows an error ´cannot transition via "reopen"`

What is the expected correct behavior?

Merge request reopened

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com

Possible fixes

I don't know.