We have a requirement that every changeset should be rebased before sending it to Evergreen commit-queue. Recently, query team started using GitHub PR and GitHub PR does not go along very well with rebasing because rebasing would require force-push which messes up with GitHub PR conversations/threads. Instead, it supports very well merge of a topic branch with the master branch.
So, rebasing is kinda redundant requirement since engineers would do merges as PR review takes time.
Instead of requiring rebasing, it would be a smoother process if Evergreen commit-queue to handle a branch merged with the master.