Author: Frederic Massart
MDL-28346 Backup: Restore does not fail when a file is missing
http://git.moodle.org/gw?p=moodle.git;a=commit;h=16ee63b4b83f82db97caeb6967ecf287d1090628
http://github.com/moodle/moodle/commit/16ee63b4b83f82db97caeb6967ecf287d1090628
+ 2.3 en [restorefileweremissing,core_backup]