Comment on first context line moves to comment on first added line

Steps to Reproduce

1. Create a branch
2. Add some lines at the top of a file (1 or more)
3. Push the branch
4. Create a pull request with the branch as source
5. Comment on the first line in the file on the PR (which should be an added line)
6. Switch to side-by-side diff
7. Comment on the first context line in the file on the TO side of the file (the right-hand-side)
8. Refresh the page

Expected Results

The comment on the first context line should show on the first context line

Actual Results

The comment on the context line will jump to the first line

Notes

See the attached video: comment-jumps-line.mp4

There's even stranger behaviour if you add multiple lines to the top of the file: comment-jumps-comment.mp4 The comment on the first context line will always jump to the comment on the first line, even if there are other comments between them.

This requires there being a comment on the first line of the file. If there's not, this won't happen.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available