Author: Tim Hunt
MDL-59929 signup: inprove usability when duplicate email entered
http://git.moodle.org/gw?p=moodle.git;a=commit;h=2b2967ee56ab2d9c9802e6f112cc4f7342b547b2
http://github.com/moodle/moodle/commit/2b2967ee56ab2d9c9802e6f112cc4f7342b547b2
+ 3.4 en [emailexistssignuphint,core]
+ 3.4 en [emailexistshintlink,core]