Author: Tim Hunt
MDL-56136 restore: better error handling copying file at start
http://git.moodle.org/gw?p=moodle.git;a=commit;h=70e85280f4abebc298e27a24099b655475d5ed3b
http://github.com/moodle/moodle/commit/70e85280f4abebc298e27a24099b655475d5ed3b
+ 3.2 en [errorcopyingbackupfile,core_backup]