The problem at hand was that an installer component
of a "DVD class" image does use/cleanup/installer
while installable LiveCD component gets broken by that
(livecd-install -> installer-scripts-remount-stage2
which gets removed as installer-*).

Split those.

I keep forgetting that CLEAUP_PACKAGES come with
/var/lib/{apt,rpm} purge, gotta do something...

This is a sort of anti-feature which removes and not builds;
still with mkimage-profiles' approach we can at least build
up the removal procedures as well.

It's what triggered the tagged scripts, BTW.