For QA, it's not super easy to test since there's no link to the edition of a draft but basically to test it you can try to create a content or update an existing one then click on save to save/create a draft and to retrieve the version id and then load the following URL:
/ez#/edit/<urlencoded REST content id>/version/<urlencoded REST version id>/<languageCode>
which gives something like:
After that, you can normally operate in the edit form. The main difference to expect is on redirection if you edit a DRAFT of a content which has never been published. In this case after discard or by closing the edit view, you are redirected to the dashboard.