I should have been more specific. If e.g. an LC_MESSAGE is set that cannot be found it returns "initialization failed" and nothing more... See the bug report.
Spent >1h this morning trying to get some demonstrator running... So I thought rather share it... 

----- Reply message -----
Von: "Daniel P. Berrange" <berrange@redhat.com>
An: "Fuchs, Andreas" <andreas.fuchs@sit.fraunhofer.de>
Cc: "libvir-list@redhat.com" <libvir-list@redhat.com>
Betreff: [libvirt] [PATCH] Be more clever and verbose about localization-initialization.
Datum: Mo., Okt 7, 2013 17:52

On Mon, Oct 07, 2013 at 03:47:48PM +0000, Fuchs, Andreas wrote:
> Currently libvirt fails with an uninformative error message
> if no translations are found.

I don't see any failure if I delete all the libvirt.mo files.

What are you actually doing to trigger an error, and what is the
exact error you get.

Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|