Author: Dan Bennett
MDL-49104 repository_s3: backport of MDL-43725
http://git.moodle.org/gw?p=moodle.git;a=commit;h=116f2c571443d14c41c29dd1a2405a42fa1409cf
http://github.com/moodle/moodle/commit/116f2c571443d14c41c29dd1a2405a42fa1409cf
+ 2.8 en [endpoint,repository_s3]