Caused by rBe65c78cd43aa.
Since above commit, only geometry and lights received the update,
previous to this check an instancer would receive that is well (in case
of 'is_updated_shading').
Now check for an instancer (checking OB_DUPLI via ob.is_instancer --
more finegrained checks could be made here) and do an update then as well
(in case of 'is_updated_shading' of course)