well, I might have done something wrong here...
I removed yaourt and package query as suggested, merged pacnew file to pacman.conf, and then launched the updates.
after that , i couldn't re-install yaourt nor package query.
After reboot, well... I can't boot !
I end up in a rescue shell , with ''can't find root'' message, and a useless keyboard, I can't type...
An idea someone ?
Now when I tried to merge my new pacman.conf I found that I did not recieve any pacman.conf.pacnew. Any on ideas why this happened.
If you did not change the original pacman.conf, it will just be updated with the new version. See the pacnew wiki page for how it works.
This answers the question. Thank you.