/usr/share/doc/libboost-timer1.65.1/changelog.Debian.gz is in libboost-timer1.65.1 1.65.1+dfsg-0ubuntu5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libboost-timer1.65.1/../libboost-system1.65.1/changelog.Debian.gz