Comment 8 for bug 634387

Looks like the code in sysvinit-2.87dsf/debian/initscripts.postinst that tries to preserve an existing motd by turning it into a motd.tail only makes sense if /etc/motd isn't already symlink to a generated file.

#
# Set up motd stuff, putting variable file in /var/run/
#
if [ ! -f /etc/motd.tail ]
then
        if [ -f /etc/motd ]
        then
                sed 1d /etc/motd > /etc/motd.tail
                [ -s /etc/motd.tail ] || rm -f /etc/motd.tail
        fi
fi

should be

#
# Set up motd stuff, putting variable file in /var/run/
#
if [ ! -f /etc/motd.tail ]
then
        if [ -f /etc/motd -a ! -L /etc/motd ]
        then
                sed 1d /etc/motd > /etc/motd.tail
                [ -s /etc/motd.tail ] || rm -f /etc/motd.tail
        fi
fi

The additional "-a ! -L /etc/motd" part would make the /etc/motd to /etc/motd.tail only happen if /etc/motd was not a symlink.