Easiest way might be to insert a spin keyword in the call to tetrahedronSpectrum() on line 54 of kdosbulk.py:
dos[j] = density_of_states.tetrahedronSpectrum(energies,spin=Spin.Down)[Ne/2]
Then you know for sure what you get back.
(Note: actual code uses the variable i instead of [j], but that doesn't work here on the Forum.)