Automattic/Co-Authors-Plus — pull request #90 by STRML (2012-11-29 20:32:27+00:00)
Title: Fix for pull 67: Map author slugs to user_nicename

Pull 67 was incomplete. Contains wp-admin fixes to complete the move to user_nicename.

Essentially, the hidden field in the wp-admin post edit screen passes user_login to the backend, which then attempts to look up a user by user_nicename. This works in most cases except when users have an email address as a login name, which converts to a url safe user_nicename (e.g. "mail@example.com" -> "mailexample-com").

This pull fixes this issue by exporting user_nicename to the template and passing it via javascript to the hidden field.