Bug#991479: systemd: /etc/sysctl.d/99-sysctl.conf gets overwritten even with --force-confold

[Franziska Kunsmann]

Package: systemd
Version: 247.3-6
Severity: important

Dear Maintainer,

I'm upgrading my systems periodically using:
    DEBIAN_FRONTEND=noninteractive apt-get -y -q -o Dpkg::Options::=--force-confold dist-upgrade

The systemd debian package will silently overwrite
/etc/sysctl.d/99-sysctl.conf with a symlink to /etc/sysctl.conf

If a user changes 99-sysctl.conf to a regular file and puts some changes
into that file, these changes will get lost during the upgrade, thus
possibly breaking systems which depend on those changes.

I have verified this occurs in debian buster and bullseye. The current
experimental package 249.2-1 also includes this symlink in its
systemd.links file.

-- Package-specific info:

-- System Information:
Debian Release: 11.0
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-8-amd64 (SMP w/32 CPU threads)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
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: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages systemd depends on:
ii  adduser                          3.118
ii  libacl1                          2.2.53-10
ii  libapparmor1                     2.13.6-10
ii  libaudit1                        1:3.0-2
ii  libblkid1                        2.36.1-7
ii  libc6                            2.31-12
ii  libcap2                          1:2.44-1
ii  libcrypt1                        1:4.4.18-4
ii  libcryptsetup12                  2:2.3.5-1
ii  libgcrypt20                      1.8.7-6
ii  libgnutls30                      3.7.1-5
ii  libgpg-error0                    1.38-2
ii  libip4tc2                        1.8.7-1
ii  libkmod2                         28-1
ii  liblz4-1                         1.9.3-2
ii  liblzma5                         5.2.5-2
ii  libmount1                        2.36.1-7
ii  libpam0g                         1.4.0-9
ii  libseccomp2                      2.5.1-1
ii  libselinux1                      3.1-3
ii  libsystemd0                      247.3-6
ii  libzstd1                         1.4.8+dfsg-2.1
ii  mount                            2.36.1-7
ii  systemd-timesyncd [time-daemon]  247.3-6
ii  util-linux                       2.36.1-7

Versions of packages systemd recommends:
ii  dbus  1.12.20-2

Versions of packages systemd suggests:
ii  policykit-1        0.105-31
ii  systemd-container  247.3-6

Versions of packages systemd is related to:
pn  dracut           <none>
ii  initramfs-tools  0.140
ii  libnss-systemd   247.3-6
ii  libpam-systemd   247.3-6
ii  udev             247.3-6

-- Configuration Files:
/etc/systemd/journald.conf changed [not included]

-- no debconf information