added check in set_xy for density == Undef but T != Undef. Failure to check for this condition had resulted in convergence to the wrong root for Hydrogen.
added check in set_xy for density == Undef but T != Undef. Failure to check for this condition had resulted in convergence to the wrong root for Hydrogen.

imitrichev/cantera,imitrichev/cantera,imitrichev/cantera,imitrichev/cantera,Heathckliff/cantera,Heathckliff/cantera,Heathckliff/cantera,imitrichev/cantera,Heathckliff/cantera,Heathckliff/cantera,imitrichev/cantera,Heathckliff/cantera