Merge request dependencies in MR widget don't update completely when dependent MR is merged

Summary

When all dependent MRs are merged, the "merge" button on the downstream MR goes green, but the descriptive text doesn't change

Steps to reproduce

I set up cross-project dependencies: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/15545 -> https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/30238

The MR correctly showed as "Depends on 1 merge request being merged".

I then merged the EE MR, and watched the CE MR's widget.

The merge button went green, but the list of dependent MRs, and the summary text, did not:

Refreshing the page correctly shows the expected state.

What is the current bug behavior?

MR doesn't fully update its state when unblocked

What is the expected correct behavior?

MR widget should correctly summarize current state

Output of checks

This bug happens on GitLab.com

Possible fixes

This seems frontend to me. We correctly return the list of blocking MRs, and the fact of the merge, in the xhr response we poll. It just doesn't update all state. It's a little confusing, but doesn't prevent you from merging.