Skimage.transform.warp could use _warp_fast for order 0


I was taking a look at skimage.transform.warp and it seems that it use the Cython routine only for order 1-3, due to this conditon:

if order in (0, 3) and not map_args:

However, looking at _warp_fast in _warps_cy.pyx it seems like there exists an implementation for order 0:

if order == 0:
        interp_func = nearest_neighbor_interpolation[np_floats, np_floats, np_floats]

Is there a reason for this limitation?