Author: Dan Bennett
MDL-49104 repository_s3: backport of MDL-43725
http://git.moodle.org/gw?p=moodle.git;a=commit;h=5b1e0822ac997f450cb6a7d5e693ca483b1aedcc
http://github.com/moodle/moodle/commit/5b1e0822ac997f450cb6a7d5e693ca483b1aedcc
+ 2.7 en [endpoint,repository_s3]