Repository graph should have visual difference between branches and tags

This is essentially the same issue as #325877 (closed) and #1539 (closed). Both issues were closed without resolution.

Problem: Repository graphs currently display branches and tags with the same style (white text on dark gray "bubble") and this makes it difficult to distinguish them at a glance.

Suggestion: It would be preferable to have a different visual style for branches and tags. For example, branches could retain the dark gray bubble, while tag bubbles could adopt the colour of the graph nodes; something like the image below. Of course, other solutions exist.

Thanks.