/usr/share/doc/libgetfem++-dbg/changelog.Debian.gz is in libgetfem++-dbg 4.2.1~beta1~svn4482~dfsg-2build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgetfem++-dbg/../libgetfem4++/changelog.Debian.gz