Hi Christophe,
Yeah, agreed. This turned out to be a problem with version 0.8.0-alpha5, and was fixed in 0.8.0-alpha6, released at the start of this month.
Ubuntu packages for that release weren't created, but instead will be created for the 0.8.0-alpha7 release, which came out earlier today.
You're probably best to compile 0.8.0-alpha7 from source for now, as it may take up to 2 weeks for the new packages to be created.
Luckily it's
really easy, with simple step by step instructions for Ubuntu here:
http://www.salasaga.org/wiki/index.php/HowToInstallOnUbuntuDoes that help?