MLP learner: fix bug where Y.shape can be (n,)
MLP learner: fix bug where Y.shape can be (n,)

cheral/orange3,qPCR4vir/orange3,qPCR4vir/orange3,cheral/orange3,qPCR4vir/orange3,kwikadi/orange3,cheral/orange3,kwikadi/orange3,qPCR4vir/orange3,kwikadi/orange3,qPCR4vir/orange3,kwikadi/orange3,cheral/orange3,kwikadi/orange3,qPCR4vir/orange3,cheral/orange3,cheral/orange3,kwikadi/orange3