  Using $N$-body simulations with massive neutrino density perturbations, we
detect the scale-dependent linear halo bias with high significance. This is the
first time that this effect is detected in simulations containing neutrino
density perturbations on all scales, confirming the same finding from separate
universe simulations. The scale dependence is the result of the additional
scale in the system, i.e. the massive neutrino free-streaming length, and it
persists even if the bias is defined with respect to the cold dark matter plus
baryon (instead of total matter) power spectrum. The separate universe approach
provides a good model for the scale-dependent linear bias, and the effect is
approximately $0.25f_\nu$ and $0.43f_\nu$ for halos with bias of 1.7 and 3.5,
respectively. While the size of the effect is small, it is ${\it not}$
insignificant in terms of $f_\nu$ and should therefore be included to
accurately constrain neutrino mass from clustering statistics of biased
tracers. More importantly, this feature is a distinct signature of
free-streaming particles and cannot be mimicked by other components of the
standard cosmological model.
