The ornamental design for a champagnebottle, as shown and described.
FIG. 1 is a front elevation of a champagne bottle;
FIG. 2 is a rear elevation of the champagne bottle;
FIG. 3 is a left-hand side elevation of the champagne bottle, the
right-hand side elevation being a mirror image thereof, except for the
writing on the labels; and,
FIG. 4 is a top plan view of the champagne bottle.
The portion of the bottom of the champagne bottle that is not shown in the
drawings does not form part of the claimed design.