[.992] bug no grateful pioneers

Just saved some villigers from wildlings.  They were grateful, and were supposed to join me as a new pioneer unit.  no such unit appeared.  I had room in my army, and actually the little 2 in a circle appeared that I think means that there are two stacks in the same space, but there was no second stack, and no unit of pioneers.  Made me sad, as I could have used them, and the fight was rather hard.