Merged MR still showing as open

Summary

@ernstvn was merging my (gitlab-com/www-gitlab-com!3491 (closed) ) MR during the latest 8.13.0 RC3 deployment. GitLab kept saying that the merge was in progress but it eventually merged (according to email and commit log). However, the MR URL itself is still showing as open and discussions has been disabled. I also had it remove source branch after successful merge so now it's in super limbo stage.

Steps to reproduce

Unknown

Expected behavior

MR should display as merged, discussions should stay intact

Actual behavior

MR is showing up as open, discussion disappeared. Only option is to close the MR.

Relevant logs and/or screenshots