Git commits in Moodle 3.1.0 by Josh Marshall

commit 86a77c91959d1fab696bafd8b1d7ba142cc5782f
Author: Josh Marshall <josh.marshall@netspot.com.au>
Date:   Thu, 29 Oct 2015 13:21:13 +0800
Tag:    v3.1.0-beta

MDL-52930 forum: Correct get_unmailed_posts logic