Bug#995006: init-system-helpers: deb-systemd-helper does not call daemon-reload despite unit files were changed

[Vasyl Gello]

Package: init-system-helpers
Version: 1.60
Severity: important
X-Debbugs-Cc: mattia at debian.org, mbiebl at debian.org

Dear colleagues,

I noticed that systemd keeps older versions of unit files even after
I explicitly rebuilt the package with new contents of unitfiles.

I decided to track down the issue and found that '$changed_sth' is
set to 1 only when **links** to systemd units are somehow updated,
i.e:

    - make_systemd_links
    - remove_links
    - mask_service
    - unmask_service

Furthermore, 'dh_installsystemd' does place 'systemctl daemon-reload'
in postrm script, but relies on conditional invocation of the same 
inside 'deb-systemd-helper' for postinst one.

To reproduce, you need a package installing systemd units.
First you install the package version with one contents of systemd unit,
then install another version with changed content of the same
systemd unit, and typing `systemctl status service` shows you old
configuration of service.

Cheers,
Vasyl   

-- System Information:
Debian Release: bookworm/sid
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'buildd-unstable'), (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-8-amd64 (SMP w/6 CPU threads)
Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=C, LC_CTYPE=C (charmap=UTF-8) (ignored: LC_ALL set to en_US.UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /bin/dash
Init: unable to detect

Versions of packages init-system-helpers depends on:
ii  perl-base  5.32.1-5

init-system-helpers recommends no packages.

init-system-helpers suggests no packages.

Versions of packages init-system-helpers is related to:
pn  insserv  <none>

-- no debconf information