Bug#1053749: systemd-sysusers: on WSL1, /etc/passwd lock fails, breaks other dpkg postinst

[Max P.]

Package: systemd
Version: 254.5-1
Severity: normal
X-Debbugs-Cc: max+bugs at prehl.us

Dear Maintainer,

I am new to submitting bug reports so please bear with me.

I am running Debian Sid in WSL1. As of a few releases ago, systemd and 
systemd-timesyncd started using systemd-sysusers in their dpkg postinst
scripts. It was during some system upgrades that I found out that 
systemd-sysusers is quite broken on the WSL1 system due to a bad lock 
implementation.

You can see several reports in this post:
- https://superuser.com/a/1805742/1298503

I was able to work around this issue by following some of the advice in
the thread.  Moving the postinst scripts temporarily, then running dpkg
--configure, then putting them back.

It was while exploring these scripts that I found the references to
systemd-sysusers.

I tried using systemd-sysusers on it's own and it will not work AT ALL,
it only produces the error:

`Failed to take /etc/passwd lock: Permission denied`

Because it was so badly broken, i also opened a report on the systemd
upstream repo:
- https://github.com/systemd/systemd/issues/29512

I'm hoping at the very least that Debian can build in some fallbacks in
the postinst scripts so that we are still able to update our systems on
WSL1 without intense workarounds.


-- Package-specific info:

-- System Information:
Debian Release: trixie/sid
  APT prefers testing
  APT policy: (650, 'testing'), (600, 'unstable'), (500, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 4.4.0-19041-Microsoft (UP)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: unable to detect

Versions of packages systemd depends on:
ii  libacl1            2.3.1-3
ii  libaudit1          1:3.1.1-1
ii  libblkid1          2.39.2-2
ii  libc6              2.37-12
ii  libcap2            1:2.66-4
ii  libcryptsetup12    2:2.6.1-5
ii  libfdisk1          2.39.2-2
ii  libgcrypt20        1.10.2-3
ii  libkmod2           30+20230601-2
ii  liblz4-1           1.9.4-1
ii  liblzma5           5.4.4-0.1
ii  libmount1          2.39.2-2
ii  libp11-kit0        0.25.0-4
ii  libseccomp2        2.5.4-1+b3
ii  libselinux1        3.5-1
ii  libssl3            3.0.11-1
ii  libsystemd-shared  254.5-1
ii  libsystemd0        254.5-1
ii  libzstd1           1.5.5+dfsg2-2
ii  mount              2.39.2-2
ii  systemd-dev        254.5-1

Versions of packages systemd recommends:
ii  dbus [default-dbus-system-bus]   1.14.10-1
ii  systemd-timesyncd [time-daemon]  254.5-1

Versions of packages systemd suggests:
ii  libfido2-1            1.13.0-1
pn  libqrencode4          <none>
pn  libtss2-esys-3.0.2-0  <none>
pn  libtss2-mu0           <none>
pn  libtss2-rc0           <none>
pn  polkitd               <none>
ii  python3               3.11.4-5+b1
pn  python3-pefile        <none>
pn  systemd-boot          <none>
pn  systemd-container     <none>
pn  systemd-homed         <none>
pn  systemd-resolved      <none>
pn  systemd-userdbd       <none>

Versions of packages systemd is related to:
ii  dbus-user-session  1.14.10-1
pn  dracut             <none>
pn  initramfs-tools    <none>
pn  libnss-systemd     <none>
ii  libpam-systemd     254.5-1
ii  udev               254.5-1

-- no debconf information