cubicweb-task #3471557 repair old migration [validation pending]

schema changes in http://hg.logilab.org/master/cubes/task/rev/850b714f398f weren't reflected in migration scripts

prioritynormal
typebug
done in1.8.1
load left0.000
closed by#53782c25278f [migration] Account for schema changes in 1.5
patch[migration] Account for schema changes in 1.5 [applied]