Any resolved thread in a File Comment permanently collapses all threads on the File

Summary

It's difficult to have multiple file-level discussions, because resolving any top-level "File" comments permanently and irreversibly collapses all File Comment threads.

Steps to reproduce

1. Click the "Comment on this file" button on any file in an MR
2. Leave a comment
3. Click the button again (do not reply to the first comment)
4. Leave a new comment
5. Resolve any of the comments
   • I did this by opening an issue to resolve the thread, which took me to another page
6. If you didn't leave the page, refresh the page. If you did leave, just navigate back to your MR Changes tab.

Example Project

gitlab-org/gitlab

What is the current bug behavior?

All the comments are collapsed. They cannot be re-opened.

What is the expected correct behavior?

Only the comment that was resolved should be collapsed.

Relevant logs and/or screenshots

Overview tab showing both discussions
Changes tab showing my collapsed comments

Output of checks

This bug happens on GitLab.com

Possible fixes

It's notable that I expected the "2 comments" link in the collapsed header to expand to show me the comments.

It did nothing when I clicked it, so this may just be a UI/behavior piping issue rather than a missing feature.