Bug#928840: boot hangs forever at live-config when libnss-systemd in image

[Steven Monai <smonaica@gmail.com>]

Package: live-config
Version: 5.20190415
Severity: normal

Dear Maintainer,

When the package 'libnss-systemd' is included in a debian-live image,
all attempts to boot the image fail, hanging forever at a particular
point in the boot process. The following message appears in the
console (all on one line), with the kinetic red "cylon" effect on the
left, and a time counter counting up towards infinity on the right:

``[ ***   ] A start job is running for live-config contains the
components that configure a live system during the boot process
(late userspace). (10min 1s / no limit)''

If it matters: I build my debian-live images with 'live-build', and
I include all Standard priority packages with the one-line package
list macro "! Packages Priority standard". In order to work around
this hanging-boot problem, I have been blocking the 'libnss-systemd'
package from my debian-live images via apt pinning.

I have tried adding "live-config.debug" to the boot command
line, but no additional useful information appears in the console.
And, furthermore, I cannot access the debug logs in the live
system, since tty consoles are not yet available at the point that
the live-config service hangs the boot sequence.

I have tried booting in both legacy/BIOS mode and in UEFI mode
(with secure boot disabled), and the behaviour is the always the
same: hanging boot.

I maintain a number of debian-live build recipes in salsa. The
following one can be used to create an ISO image that exhibits the
hanging boot problem (just remove the pin in 'config/apt/preferences'
before running the 'make.sh' script):

https://salsa.debian.org/smonaica-guest/sid-standard-live.git

Best regards,
-S.M.


-- System Information:
Debian Release: 10.0
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.19.0-4-amd64 (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8),
LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages live-config depends on:
ii  live-config-systemd [live-config-backend]  5.20190415

Versions of packages live-config recommends:
ii  iproute2                4.20.0-2
ii  keyboard-configuration  1.191
ii  live-config-doc         5.20190415
ii  live-tools              1:20171207
ii  locales                 2.28-10
ii  sudo                    1.8.27-1
ii  user-setup              1.81

Versions of packages live-config suggests:
ii  pciutils  1:3.5.2-5
ii  wget      1.20.1-1.1

-- no debconf information