The ornamental design for a pastrybagsupport, as shown and described.
FIG. 1 is a perspective view of the pastry bag support;
FIG. 2 is an exploded perspective view of the pastry bag support;
FIG. 3 is a front plan view of the pastry bag support of FIG. 1;
FIG. 4 is a right side plan view of the pastry bag support of FIG. 1, with the left side plan view being identical; and,
FIG. 5 is a rear plan view of the pastry bag support of FIG. 1.
The pastry bag, tips and support for the tips on the base of the pastry bag support are depicted in broken lines in FIGS. 1-5 and form no part of the claimed design.