/usr/include/python3.6dmu/bsddb3 is in python3-bsddb3-dbg 6.1.0-1build4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/include/python3.6dmu/../python3.6mu/bsddb3
/usr/include/python3.6dmu/../python3.6mu/bsddb3