/usr/share/doc/libmrpt-topography1.5/changelog.Debian.gz is in libmrpt-topography1.5 1:1.5.5-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libmrpt-topography1.5/../libmrpt-base1.5/changelog.Debian.gz