Backporting shibboleth-sp2 2.6.0+dfsg1-4 to jessie: dh-systemd, piuparts and lintian errors

[Ferenc Wágner]

Etienne Dysli-Metref <etienne.dysli-metref at switch.ch> writes:

> Since shibboleth-sp2 2.6.0+dfsg1-4 migrated to testing during the
> holidays, I'm now backporting it to jessie. So far there is nothing to
> change, however piuparts gives me the following error (which does not
> appear on stretch):
>
>> 0m34.6s ERROR: FAIL: Package purging left files on system:
>>   /etc/systemd/system/multi-user.target.wants/shibd.service -> /lib/systemd/system/shibd.service	 not owned
>>   /etc/systemd/system/shibd.service -> /dev/null	 not owned
>>   /var/lib/systemd/deb-systemd-helper-enabled/	 not owned
>>   /var/lib/systemd/deb-systemd-helper-enabled/multi-user.target.wants/	 not owned
>>   /var/lib/systemd/deb-systemd-helper-enabled/multi-user.target.wants/shibd.service	 not owned
>>   /var/lib/systemd/deb-systemd-helper-enabled/shibd.service.dsh-also	 not owned
>>   /var/lib/systemd/deb-systemd-helper-masked/	 not owned
>>   /var/lib/systemd/deb-systemd-helper-masked/shibd.service	 not owned
>
> It looked like dh-systemd wasn't properly cleaning up despite
> shibboleth-sp2-utils's postrm script looking like it would: [...]

I couldn't reproduce this on a real jessie system, only in a piuparts
chroot.  I think the reason is that piuparts removes init-system-helpers
(the home of deb-systemd-helper) before the shibboleth-sp2-utils postrm
could instruct it to clean up.  I'm not sure what we could do about
this.

> So I bumped the build-dep up a bit to: dh-systemd (>= 9.20160709).

Why?  I mean, where did this version number come from?
-- 
Feri