The ornamental design for the bread bag, as shown and described.
FIG. 1 is a perspective view of the bread bag in an open configuration;
FIG. 2 is a perspective view of the bread bag in the closed configuration;
FIG. 3 is a front perspective view of the bread bag in the open configuration;
FIG. 4 is a right side view of the bread bag of FIG. 3 in the open configuration;
FIG. 5 is a left side view of the bread bag of FIG. 3 in the open configuration;
FIG. 6 is a rear view of the bread bag in the open configuration;
FIG. 7 is a top view of the bread bag in the open configuration; and,
FIG. 8 is a bottom view of the bread bag.
The portions of the drawings depicted in broken lines in FIGS. 1-8, including the straps, apertures, top loop, zipper pouch in the rear view, and the side tab are for the purposes of illustrating environment and, form no part of the claimed design.