/usr/share/doc/libpetsc-complex-3.7.7-dbg/changelog.Debian.gz is in libpetsc-complex-3.7.7-dbg 3.7.7+dfsg1-2build5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libpetsc-complex-3.7.7-dbg/../libpetsc-complex-3.7.7/changelog.Debian.gz