Show commits used when creating the pull request

At the moment, when a pull request is updated, a list is shown with which commits were added: "Blah UPDATED by adding 13 commits 4 hours ago"

It would be great if a similar list of commits were shown to indicate the commits that existed when the pull request was opened. At the moment we get "Blah OPENED this pull request 8 hours ago" with no commit summary.

We rebase and fixup commits in PRs. Sometimes comments are placed on the commits and not the diff. Those comments are available when the PR is first opened but after an update comments can be lost from the PR history.

Ideally comments shown as commits for the PR would best show up on the activity and track fixups (like Gitlab does) but that's a much harder fix and a separate request to this.