/usr/share/doc/debdelta/debdelta_suite.pdf is in debdelta-doc 0.55.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/debdelta/../debdelta-doc/debdelta_suite.pdf
/usr/share/doc/debdelta/../debdelta-doc/debdelta_suite.pdf