Git commits in Moodle 3.2.9 by Tim Hunt

commit dea378602ddbf1c269273b969a211904c1f7f93b
Author: Tim Hunt <T.J.Hunt@open.ac.uk>
Date:   Tue, 01 May 2018 02:45:47 +0800
Tag:    v3.2.9

MDL-62275 qtype_calc*: improve validation of formulae