The Spaniards also use 'em for oil and vinegar. In this size, that'd be my bet, though I know there are some "single-serving" pieces used to serve wine from the barrel by the bar and restaurant trade.
Not sure that they're necessarily very old, either.
There are a lot of Spanish workshops making things out of recycled glass, and their pieces are sometimes deceptively old-looking.
Sorry to be a cold shower,
Chris