I think the check exists to restrict the user from applying values that would be grossly impractical, like 1e-20. That said, if we want to keep the check, we could ask if the applied sum is zero;
float angvelsum = angvel.length2()
if (m_object && ( angvelsum == 0 || angvelsum > (SIMD_EPSILON*SIMD_EPSILON)))
I've got no idea how to submit patches, though.