PARIS – Over the years, the chief sommelier had forgotten they were there. And when the four bottles of 1875 Armagnac Vieux were finally unearthed from the labyrinthine wine cellar this week, they were covered in a black fungus that looked like matted cat fur. The landmark Tour d'Argent restaurant, which dates back to 1582, is cleaning out its 450,000-bottle wine cellar, considered one of the best and biggest in the world. It is putting 18,000 bottles up for auction in December, an event that has captured the imagination of French wine lovers. The restaurant is selling mostly wine but...