The inobvious issue is that while lxde-settings
is required by lxde-common and provided by both
lxde-settings-{altlinux,upstream}, we can't just
add the needed one via PACKAGES since the LISTS'
deps are expanded already with -upstream taking
lexicographical precedence.

This might become more serious if/when there are
several useful packages, -upstream isn't AFAIK
(thanks gns@ for explanation).