A lot of strange problems (Debian Testing).

[LeDechaine]

Hello guys. I don't even know where to post this. I've been using MATE for years without any issues, but after the last update, I now have to login and "startx­" because mate-session-manager is installed but doesn't seem to launch. Also, most of the MATE desktop environment... uninstalled itself, apparently. My desktop is there, background, "apps/places/system" menu bar (personal modifications included in my "apps" menu)... but I had to reinstall the mate-applet package and the network-manager applet, and most of the "system" preferences are just gone. I can't even change my background, apparently I'll need to find and reinstall the mate system apps again (themes, keyboard shortcuts, etc -- edit: wow, even mate-calc uninstalled itself).

I don't remember about any warning telling me mate-(anything) would be uninstalled during the last apt-get update/upgrade/dist-upgrade.

The strangest thing may be that the MATE logo at the top left corner is now the old "gnome foot".

Actual behaviour

Mate Desktop Environment mostly uninstalled.

Steps to reproduce the behaviour

sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade

MATE general version

1.20.1

Linux Distribution

Debian testing
$ uname -a
Linux symphony 4.16.0-2-amd64 #1 SMP Debian 4.16.12-1 (2018-05-27) x86_64 GNU/Linux

[LeDechaine]

Now, for this actual package... (sorry, as I said, did not know where to post this).
sudo dpkg-reconfigure mate-session-manager did not fix it.
sudo apt-get install --reinstall mate-session-manager either.