Place pheasants, onions, celery and garlic in a large roasting pan. Top with diced bacon. Place in a 400 degree oven and roast for 1 hour or until pheasants are evenly browned. Remove from oven, allow to cool and pull meat from pheasant breasts. Save breast meat. Cut carcasses into 4 smaller pieces and place in a large stockpot with roasted vegetables. Cover with water and bring to a boil over high heat. Reduce heat and simmer for 3 hours, stirring contents occasionally and keeping water level high enough to just cover contents. Remove pheasant pieces with tongs and pour remaining liquid through a colander to remove solids. Return liquid to pot and chicken broth, leeks, carrots, potatoes and rosemary. Bring to boil, then reduce heat and simmer until carrots just begin to soften. Add pulled pheasant breast pieces and tomatoes. Simmer for 5 minutes more, remove rosemary and serve with warm sourdough bread.