Author: Frederic Massart
MDL-51866 tool_lp: Framework scale cannot be changed once it is used
http://git.moodle.org/gw?p=moodle.git;a=commit;h=2ec1b70bcd9b85e720b24803ca8cfa4f2f02fd75
http://github.com/moodle/moodle/commit/2ec1b70bcd9b85e720b24803ca8cfa4f2f02fd75
+ 3.1 en [errorscalealreadyused,tool_lp]