Comment 11 for bug 1931088

Looks like I can at least reproduce the issue on an arm64 Canonistack machine, utilizing an armhf container:

ubuntu@focal-arm64:~$ time autopkgtest systemd --test-name=boot-and-services -U -- lxd autopkgtest/ubuntu/impish/armhf
[...]
autopkgtest [15:59:21]: test boot-and-services: [-----------------------
lxc
Created symlink /etc/systemd/system/default.target → /lib/systemd/system/graphical.target.
bash: line 1: 3532 Killed /tmp/autopkgtest.OAYOpR/build.yrL/src/debian/tests/boot-and-services 2> >(tee -a /tmp/autopkgtest.OAYOpR/boot-and-services-stderr >&2) > >(tee -a /tmp/autopkgtest.OAYOpR/boot-and-services-stdout)
autopkgtest [15:59:24]: test process requested reboot with marker boot1
Unexpected error:
Traceback (most recent call last):
  File "/usr/share/autopkgtest/lib/VirtSubproc.py", line 738, in mainloop
    command()
  File "/usr/share/autopkgtest/lib/VirtSubproc.py", line 667, in command
    r = f(c, ce)
  File "/usr/share/autopkgtest/lib/VirtSubproc.py", line 363, in cmd_reboot
    caller.hook_wait_reboot()
  File "/usr/bin/autopkgtest-virt-lxd", line 231, in hook_wait_reboot
    wait_booted()
  File "/usr/bin/autopkgtest-virt-lxd", line 104, in wait_booted
    VirtSubproc.check_exec(['lxc', 'exec', container_name, '--', 'sh', '-ec', '[ ! -d /run/systemd/system ] || systemctl start network-online.target'], timeout=60)
  File "/usr/share/autopkgtest/lib/VirtSubproc.py", line 182, in check_exec
    (status, out, err) = execute_timeout(None, timeout, real_argv,
  File "/usr/share/autopkgtest/lib/VirtSubproc.py", line 144, in execute_timeout
    (out, err) = sp.communicate(instr)
  File "/usr/lib/python3.8/subprocess.py", line 1014, in communicate
    stderr = self.stderr.read()
  File "/usr/share/autopkgtest/lib/VirtSubproc.py", line 64, in alarm_handler
    raise Timeout()
VirtSubproc.Timeout
autopkgtest [16:01:18]: ERROR: testbed failure: unexpected eof from the testbed

real 8m29.354s
user 0m8.866s
sys 0m8.141s

Let's see what we can do about it. It looks like a dnsmasq (security-)update was pushed to Bionic++ on 2021-06-02 – about the same time that this test started failing on Bionic++ ... I wonder if this might somehow be related? ... need to further investigate.