A "Create Merge Request" button is displayed in activity > push events although one already open

I see this, although I've already submitted a merge request.

I am still able to submit a new MR, but then find myself here:

Seems like the button should only be shown if creating a merge request is a viable option.

Changed title: A "Create Merge Request" is displayed in activity > push events although one already open → A "Create Merge Request" button is displayed in activity > push events although one already open

moved from gitlab-foss#21524 (moved)