There's a little typo in that git commit: http://anonscm.debian.org/gitweb/?p=tasksel/tasksel.git;a=commit;h=0c8496f3f1808b8dff728b6af72825e4f02c3c60 > Replace gdm3 by lightdm in lxde-desktop task. Closes: #683349 should be not #683349, but #683345.