Resolve WIP button disappeared from WIP merge requests

Summary

With a merge request with a title prefixed with WIP:, the button to resolve the WIP status no longer shows up to let you remove the WIP state in one click on the merge request.

Steps to reproduce

1. Create a merge request of a project with WIP: prefix in the title

Example Project

This project's merge request exhibits the behavior for me: osslugaru/lugaru!27

What is the current bug behavior?

The Resolve WIP status button is missing from the UI to let you resolve the status in one click.

What is the expected correct behavior?

The Resolve WIP status button should exist and let you resolve the status in one click.

Output of checks

This bug happens on GitLab.com.