Given that neither lubuntu-meta or xubuntu-meta includes ubuntu-release-upgrader-core (which would perform the upgrade and use DistUpgrade.cfg), this seems a bit strange to me.
Could you provide some more information as to what problem you are trying to solve? One way to test your changes would be to run do-release-upgrade then cancel the upgrade after the dist upgrader tarball is downloaded, switch to whatever directory it is in /tmp/ e.g. /tmp/dist-upgrader-XYZ and modify data/DistUpgrade.cfg then run the vivid symlink there as root.
Finally, having lubuntu-core as a key dependency of itself seems rather redundant.
Given that neither lubuntu-meta or xubuntu-meta includes ubuntu- release- upgrader- core (which would perform the upgrade and use DistUpgrade.cfg), this seems a bit strange to me.
Could you provide some more information as to what problem you are trying to solve? One way to test your changes would be to run do-release-upgrade then cancel the upgrade after the dist upgrader tarball is downloaded, switch to whatever directory it is in /tmp/ e.g. /tmp/dist- upgrader- XYZ and modify data/DistUpgrad e.cfg then run the vivid symlink there as root.
Finally, having lubuntu-core as a key dependency of itself seems rather redundant.