Author: Andrew Davis
rss MDL-24509 added some support for 1.9 rss feed requests
http://git.moodle.org/gw?p=moodle.git;a=commit;h=8a73f57081b36ea72050050ee81be85fde37bfd6
http://github.com/moodle/moodle/commit/8a73f57081b36ea72050050ee81be85fde37bfd6
+ 2.0 en [rsserrorguest,core]