Author: Petr Skoda
MDL-28595 explain the need to install into new db if something fails during the initial install
http://git.moodle.org/gw?p=moodle.git;a=commit;h=1ad8143a30ce8bd8ac750a35ba12851c465f3e6d
http://github.com/moodle/moodle/commit/1ad8143a30ce8bd8ac750a35ba12851c465f3e6d
+ 2.2 en [installproblem,core_error]