Author: Andrew Davis
MDL-46035 mod_survey: a string change to make an error message always correct
http://git.moodle.org/gw?p=moodle.git;a=commit;h=deaddfb6b82ea92ec735f1156fc4834fcefc2c4a
http://github.com/moodle/moodle/commit/deaddfb6b82ea92ec735f1156fc4834fcefc2c4a
+ 2.7 en [guestsnotallowed,mod_survey]