[Pkg-libvirt-maintainers] Bug#766362: libvirt-daemon-system: fails to install

[Guido Günther]

On Thu, Oct 23, 2014 at 09:02:01AM +0300, Niko Tyni wrote:
> On Wed, Oct 22, 2014 at 04:58:03PM +0200, intrigeri wrote:
> > Holger Levsen wrote (22 Oct 2014 14:06:05 GMT) :
> > >   BEGIN failed--compilation aborted at /usr/bin/deb-systemd-helper line 85.
> > 
> > ... which is shipped by the init-system-helpers package, that depends
> > on perl-modules, that ships File::Path. The attached log shows that
> > init-system-helpers and libvirt-daemon-system are unpacked before
> > perl-modules is upgraded, but after perl itself was upgraded, so with
> > the new @INC set up, it doesn't look anymore for modules in the place
> > where Wheezy's perl-modules ships File::Path (/usr/share/perl/5.14.2).
> 
>   BEGIN failed--compilation aborted at /usr/bin/deb-systemd-helper line 85.
>   dpkg: error processing archive /var/cache/apt/archives/libvirt-daemon-system_1.2.8-3_amd64.deb (--unpack):
>    subprocess new pre-installation script returned error exit status 2
> 
> The libvirt-daemon-system package is using non-essential functionality
> in a preinst script without a pre-dependency. Policy 6.5:
> 
>   The package will not yet be unpacked, so the `preinst' script cannot
>   rely on any files included in its package.  Only essential packages
>   and pre-dependencies (`Pre-Depends') may be assumed to be available.
>   Pre-dependencies will have been configured at least once, but at the
>   time the `preinst' is called they may only be in an "Unpacked" or
>   "Half-Configured" state if a previous version of the pre-dependency
>   was completely configured and has not been removed since then.

Although I don't understand why the lack of the dependency triggers an
error like the above we're lacking the PreDependeny nevertheless
(thanks for pointing this out). Since I'd rather avoid to PreDep on
init-system-helpers I wonder what would be the best solution?

The sole purpose of the preinst part is to get rid of the remains of
the libvirt-bin service files since we renamed back to the upstream
name libvirtd.

Can't we simply remove

/etc/systemd/system/multi-user.target.wants/libvirtd.service 
/var/lib/systemd/deb-systemd-helper-enabled/multi-user.target.wants/libvirtd.service
/var/lib/systemd/deb-systemd-helper-enabled/libvirtd.service.dsh-also

in lbvirt-daemon-system.preinst?

I've slightly changed the cc: list to hopefully get feedback from
people are more familiar with deb-systemd-helper than I am.
Cheers,
 -- Guido