/usr/share/doc/mate-polkit/HACKING is in mate-polkit 1.12.0-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/mate-polkit/../mate-polkit-common/HACKING
/usr/share/doc/mate-polkit/../mate-polkit-common/HACKING