/usr/share/doc/octave-gsl/NEWS is in octave-gsl 2.1.0-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/octave-gsl/../../octave/packages/gsl-2.1.0/packinfo/NEWS
/usr/share/doc/octave-gsl/../../octave/packages/gsl-2.1.0/packinfo/NEWS