The ornamental design for a transitionbag, as shown and described.
FIG. 1 is a front perspective view of a bag showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The thin dashed broken lines illustrate claimed stitching. Type 1 is the Stitching line and Type 2 is a Zipper line. The thick dotted lines illustrate portions of the transition bag and form no part of the claimed design.