The ornamental design for a blocking hatrack, as shown and described.
FIG. 1 is a left side elevational view of a blocking hat rack showing my
new design, the broken-line disclosure of a hat being for illustrative
purposes only and forming no part of the claimed design;
FIG. 2 is a bottom, front, and left side perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a left side elevational view thereof, the right side being a
mirror image of that shown; and,
FIG. 5 is a top, front, and right side perspective view thereof.