Git commits in Moodle 2.8.8 by Dave Cooper

commit 0bd275a9e20fd5bb7ce1e10e766533087a9d6701
Author: Dave Cooper <dave@moodle.com>
Date:   Thu, 11 Jun 2015 16:26:15 +0800
Tag:    v2.8.8

MDL-50062 gradebook: Fixed behaviour when changing aggregation mathods.