Good point! then the bug is the following lines in lightdm.spec
%if ! %{defined _distconfdir}
sed -e 's-/usr/etc-%{_sysconfdir}-g' -i
%{buildroot}%{_datadir}/lightdm/lightdm.conf.d/50-suse-defaults.conf
%endif
because SLE's rpm-config now has _distconfdir /etc defined, since the
definition do exist, sed doesn't execution. So it's still a bug in lightdm.