/usr/share/doc/gmt/changelog.Debian.gz is in gmt 5.4.3+dfsg-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gmt/../libgmt5/changelog.Debian.gz
/usr/share/doc/gmt/../libgmt5/changelog.Debian.gz