Comment 72 for bug 2034986

Verification (synthetic) of the XDG_SESSION_TYPE fix in Mantic:

 $ lsb_release -cs
 No LSB modules are available.
 mantic

The packages are downloaded from Launchpad librarian
since previous versions are not available in archive.

Before the fix (reverted) // 1:23.10.12
---

The XDG_CURRENT_DESKTOP variable IS NOT passed in `pkexec ... --env=`.

 $ wget https://launchpad.net/ubuntu/+source/ubuntu-release-upgrader/1:23.10.12/+build/26929436/+files/{ubuntu-release-upgrader-{core,gtk},python3-distupgrade}_23.10.12_all.deb

 $ sudo apt install -y ./ubuntu-release-upgrader-core_23.10.12_all.deb ./ubuntu-release-upgrader-gtk_23.10.12_all.deb ./python3-distupgrade_23.10.12_all.deb

 $ dpkg -s ubuntu-release-upgrader-core | grep Version:
 Version: 1:23.10.12

 $ export XDG_CURRENT_DESKTOP=just:testing

 $ strace -s 128 do-release-upgrade -d -f DistUpgradeViewGtk3 2>&1 | grep '^execve("/usr/bin/pkexec"' | grep -o -- '--env=[^"]\+'
 --env=DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus,XDG_SESSION_TYPE=tty

After the fix (reapplied) // 1:23.10.13
---

The XDG_CURRENT_DESKTOP variable IS passed in `pkexec ... --env=`.

 $ wget https://launchpad.net/ubuntu/+source/ubuntu-release-upgrader/1:23.10.13/+build/26932072/+files/{ubuntu-release-upgrader-{core,gtk},python3-distupgrade}_23.10.13_all.deb

 $ sudo apt install -y ./ubuntu-release-upgrader-core_23.10.13_all.deb ./ubuntu-release-upgrader-gtk_23.10.13_all.deb ./python3-distupgrade_23.10.13_all.deb

 $ dpkg -s ubuntu-release-upgrader-core | grep Version:
 Version: 1:23.10.13

 $ export XDG_CURRENT_DESKTOP=just:testing

 $ strace -s 128 do-release-upgrade -d -f DistUpgradeViewGtk3 2>&1 | grep '^execve("/usr/bin/pkexec"' | grep -o -- '--env=[^"]\+'
 --env=DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus,XDG_SESSION_TYPE=tty,XDG_CURRENT_DESKTOP=just:testing

Latest version (mantic-proposed) // 1:23.10.14
---

The XDG_CURRENT_DESKTOP variable IS passed in `pkexec ... --env=`.

 $ sudo add-apt-repository -yp proposed

 $ sudo apt install -y -t mantic-proposed ubuntu-release-upgrader-core

 $ dpkg -s ubuntu-release-upgrader-core | grep Version:
 Version: 1:23.10.14

 $ strace -s 128 do-release-upgrade -d -f DistUpgradeViewGtk3 2>&1 | grep '^execve("/usr/bin/pkexec"' | grep -o -- '--env=[^"]\+'
 --env=DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus,XDG_SESSION_TYPE=tty,XDG_CURRENT_DESKTOP=just:testing