Comments in collapsed diffs are hard to find

Summary

It's very hard to find comments in collapsed diffs.

Steps to reproduce

1. Create a large commit with collapsed diffs.
2. Expand a diff.
3. Comment on a line in that diff.
4. Open the commit again in another window.

Expected behavior

Either expand the diff automatically if it has a comment, or show an icon to indicate that there are hidden comments in the header.

Actual behaviour

The commit is shown with the diff containing the comment collapsed. The comment is hidden and hard to find.

Relevant logs and/or screenshots

Example link: nkovacs/gitlab-ci-multi-runner@bbca5a3d

There's a comment on Godeps/_workspace/src/github.com/minio/minio-go/API.md