Comment 3 for bug 237317

I'm still confused:

$ wget http://archive.ubuntu.com/ubuntu/pool/main/c/cupsys/libcupsys2_1.3.7-1ubuntu3_amd64.deb
$ dpkg -c libcupsys2_1.3.7-1ubuntu3_amd64.deb | grep changelog.gz
-rw-r--r-- root/root 8733 2008-04-01 22:32 ./usr/share/doc/libcupsys2/changelog.gz

It's not a symlink, it's a regular file as it should be. Also after installation. The postinst doesn't do any symlinking. So I honestly don't know what went wrong on your system, and how to reproduce it.