Comment 17 for bug 1846787

Verification done on xenial-proposed.

With the new systemd and dbus packages, there are no leaked sessions after the test-case of ssh loop.

The autopkgtests regressions reported previously are unrelated to this change (comments #11 to #16).

cheers,
Mauricio

Setup
---

$ sudo snap install --beta --classic multipass

$ multipass launch --cpus 2 --mem 8G --disk 8G --name lp1846787 xenial
$ multipass shell lp1846787

$ lsb_release -cs
xenial

$ ssh-keygen -t rsa -f ~/.ssh/id_rsa -N ''
$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
$ sudo apt update && sudo apt -y upgrade && sudo reboot

xenial-updates: there are leaked sessions after ssh loop. (bad)
---

$ multipass shell lp1846787

$ dpkg -s systemd dbus | grep ^Version:
Version: 229-4ubuntu21.22
Version: 1.10.6-1ubuntu3.4

$ find /run/systemd/system/ -name 'session-*.scope.d' | wc -l
1

$ find /run/systemd/system/ -name '*.scope.d'
/run/systemd/system/session-1.scope.d

$ for i in {1..1000}; do sleep 0.01; ssh localhost sleep 1 & done
...
[1000] 12191

$ jobs
$

$ find /run/systemd/system/ -name 'session-*.scope.d' | wc -l
32

$ find /run/systemd/system/ -name 'session-*.scope.d'
/run/systemd/system/session-906.scope.d
/run/systemd/system/session-896.scope.d
/run/systemd/system/session-848.scope.d
...
/run/systemd/system/session-1.scope.d

xenial-proposed: there are NO leaked sessions after ssh loop. (good; tested 3x)
---

$ echo 'deb http://archive.ubuntu.com/ubuntu xenial-proposed main' | sudo tee /etc/apt/sources.list.d/xenial-proposed.list
$ sudo apt update && sudo apt -y install systemd dbus && sudo reboot

$ multipass shell lp1846787

$ dpkg -s systemd dbus | grep ^Version:
Version: 229-4ubuntu21.23
Version: 1.10.6-1ubuntu3.5

$ find /run/systemd/system/ -name 'session-*.scope.d' | wc -l
1

$ find /run/systemd/system/ -name 'session-*.scope.d'
/run/systemd/system/session-1.scope.d

$ for i in {1..1000}; do sleep 0.01; ssh localhost sleep 1 & done
...
[1000] 12462

$ jobs
$

$ find /run/systemd/system/ -name 'session-*.scope.d' | wc -l
1

$ find /run/systemd/system/ -name 'session-*.scope.d'
/run/systemd/system/session-1.scope.d