Fix the post-commit creation to also create a draft.
Review Request #5780 — Created May 7, 2014 and submitted — Latest diff uploaded
Using the post-commit UI would create a ReviewRequest object with public=False,
but wouldn't create an associated draft. This meant that the review request
looked like it was public but wasn't.
Created a post-commit review request and saw the "This review request is not
yet public" banner.