/usr/lib/pd/extra/sigpack/LICENSE.txt is in pd-sigpack 0.0.4.2-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/pd/extra/sigpack/../../../../share/common-licenses/GPL-2
/usr/lib/pd/extra/sigpack/../../../../share/common-licenses/GPL-2