On Sat, 14 Jul 2018 21:09:41 -0700 Mike Bird mgb-trinity@yosemite.net wrote:
(Manually) changed /etc/X11/default-display-manager back to tdm-trinity
This broke your installation and invalidated subsequent tests as /etc/X11/default-display-manager no longer matches the value in /var/cache/debconf/config.dat
dpkg-reconfigure is the way to go.
No this is irrelevant. tdm-trinity and slim install scripts do not check this on install, only if debconf question about display manager was answered.