Only exclude commit authors in merge request approvers
With https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9007, anyone who rebases or amends a commit in a merge request will be tagged as a committer, even if there were no changes made. This is surprising behavior and prevents reviewers from even touching a merge request.
Instead, we loosen the restriction to look only at the commit authors.
Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/9787
CE backport: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/25294
Edited by Stan Hu