Split/auto publish

LMS-11017 https://openedx.atlassian.net/browse/LMS-11017
If you can generate a state where the course root has not been published but you're calling this, then we have a code gap in auto publish. That is, creating the course root should auto publish it; so, that line in copy should never get triggered. It merely means that the course has never been published (and we should change the message to `Must copy course root {} before any other part of the course.`)