Git commits in Moodle 2.4.x by Kyle Temkin

commit b64526c715198eccb0413a5b33d8623d20c0e111
Author: Kyle Temkin <ktemkin@binghamton.edu>
Date:   Fri, 21 Jun 2013 15:28:59 +0800
Tag:    v2.4.5

MDL-40264 fix essay handling of zero-string response