/usr/share/doc/postfix-mysql/changelog.Debian.gz is in postfix-mysql 2.11.0-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/postfix-mysql/../postfix/changelog.Debian.gz
/usr/share/doc/postfix-mysql/../postfix/changelog.Debian.gz