Git commits in Moodle 2.1.7 by Jonathon Fowler

commit 790f68fd9204fea9cdd4b17092a08e4db8e1e4e1
Author: Jonathon Fowler <fowlerj@usq.edu.au>
Date:   Wed, 09 May 2012 09:51:18 +0800
Tag:    v2.1.7

MDL-32863 question: fix for Oracle ambiguous column error