/usr/share/doc/libxapian-1.3-5-dbg/changelog.Debian.gz is in libxapian-1.3-5-dbg 1.3.4-0ubuntu6.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libxapian-1.3-5-dbg/../libxapian-1.3-5/changelog.Debian.gz