Automattic/Co-Authors-Plus — pull request #140 by danielbachhuber (2014-03-07 19:07:40+00:00)
Title: add_coauthors should update post_author if append = false

`add_coauthors` currently just adds or appends author terms to the post.

If `$append = false`, it should also update the `post_author` with the first user assigned to the post (if there is at least one user assigned as a byline).