/usr/share/man/man1/db_dump.1.gz is in db-util 1:5.3.21~exp1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man1/db5.3_dump.1.gz
/usr/share/man/man1/db5.3_dump.1.gz