Author: Tim Hunt
MDL-20636 Implement the ability to only upgrade some of the quiz attempts during the main upgrade.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=1027301215fa504938b08e6caa76016c93b62a44
http://github.com/moodle/moodle/commit/1027301215fa504938b08e6caa76016c93b62a44