Using mappedBy "none" does not work in unit testing implementation

Migration of the jira issue: https://jira.grails.org/browse/GRAILS-11285

This issue happens during unit tests where I cannot mock my domain class. I upgraded my test cases to use grails 2.4.5 to no avail, but I attached that test project anyway.

grails24test.tar.gz:
https://onedrive.live.com/redir?resid=3266892724B725AB%21152849
