It allows pad/via holes to ber plotted at actual size, small size, or not.
This option exists in GUI, but was missing in kicad-cli.
(cherry picked from commit f18feb2a46)
ADDED: The -n or --negative option for exporting negative svg or pdf plots
from kicad-cli. Example usage: kicad-cli pcb export svg -n -l B.Cu board.kicad_pcb