This “deformation_layer” isn’t part of upstream Caffe, so maybe it’s only their code to make the use of BLAS cleaner.
// reshape top blob to requested shape
vector out_shape;
out_shape.push_back(batch_size_);
if( param.nz() > 0) out_shape.push_back(param.nz());
out_shape.push_back(param.ny());
out_shape.push_back(param.nx());
out_shape.push_back(param.ncomponents());
top[0]->Reshape( out_shape);