The ornamental design for a hammockbag, as shown and described.
FIG. 1 is a front perspective view of a hammock bag showing my new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a top perspective view thereof;
FIG. 4 is a bottom perspective view thereof;
FIG. 5 is a front perspective view thereof shown in an alternate and partially closed position; and,
FIG. 6 is a front perspective view thereof shown in an alternate and open position.
The broken line showings of a hammock bag in FIGS. 1-6 are for the purpose of illustrating the environment in which the design is associated and form no part of the claimed design.