No user notice when MWPS is unset when resolved thread gets new comment

Summary

You're able to set a merge request to merge when pipeline succeeds, but it is unset if a new comment is added to a thread that then marks it as unresolved.

Steps to reproduce

• Start a thread on an MR (All discussions must be resolved must be checked in project MR settings)
• Set MR to merge when pipeline succeeds
• Add comment to resolved thread, marking it as unresolved
• If pipeline succeeds, nothing happens
• You need to resolve the thread, cancel the MWPS, and then merge again

Example Project

https://gitlab.com/gitlab-org/design.gitlab.com/merge_requests/1468#note_191974049

What is the expected correct behavior?

Some sort of user notice that explains what is happening