Cut the rabbit up into about 12 pieces and put in a good-sized bowl with 2 tablespoons of olive oil, the wine, juniper berries, garlic, bay leaves and thyme, and a few good grinds of black pepper. Leave, covered, for an hour or two to marinate, in the fridge if it is a warm day.
Heat the remaining 3 tablespoons of oil in a large deep pan. Lift the rabbit pieces from the marinade (reserve the marinade), shake out, then brown well on all sides. Add the pancetta and fry that too, until golden. Salt the rabbit pieces, then add the marinade to the pan along with the water. Cover and simmer for 30 minutes. Add half the grapes, cover again and simmer for 30-40 minutes or so. Add the rest of the grapes and simmer, uncovered, for 10 minutes more to slightly thicken the juices in the pan. Check the seasoning and serve.