Add the onion, carrots, garlic and jalapeño to the casserole and cook over moderate heat until slightly softened, about 5 minutes. Return the rabbit and bacon to the pan. Add the beer and chicken stock and bring to a boil. Cook partially covered over low heat until the rabbit is tender, about 1 1/2 hours. Transfer the rabbit to a platter and boil the sauce until slightly reduced, about 5 minutes. In a small bowl, whisk the flour with 2 of tablespoons water and whisk into the sauce. Cook over high heat until thickened and no floury taste remains, about 2 minutes.