Because of some changes performed to the multichoice qtype
for Moodle 2.6, older sites are not able to upgrade properly.
This commits does introduce DB introspection to decide which
table and column names must be used. Nasty but enough.
Note MDL-52298 has been created about to avoid/minimize the
chances of this happening again.
Eloy Lafuente (stronk7)
95f83b70b0