[arch-general] pacman upgrade confusion

[message]

> Readers,
> 
> An announcement
> (https://www.archlinux.org/news/required-update-to-pacman-501-before-2016-04-23/)
> states that users must upgrade to pacman501.
> 
> pacman -S pacman
> warning: pacman-5.0.0-1 is up to date -- reinstalling
> resolving dependencies...
> looking for conflicting packages...
> 
> Packages (1) pacman-5.0.0-1
> 
> Firstly, I tried:
> 
> yaourt -Syua
> package-query: error while loading shared libraries: libalpm.so.9:
> cannot open shared object file: No such file or directory
> 
> Then:
> 
> pacman -S pacman
> warning: pacman-5.0.0-1 is up to date -- reinstalling
> resolving dependencies...
> looking for conflicting packages...
> 
> Packages (1) pacman-5.0.0-1
> pacman --version
> 
>   .--.                  Pacman v5.0.0 - libalpm v10.0.0
> / _.-' .-.  .-.  .-.   Copyright (C) 2006-2016 Pacman Development Team
> \  '-. '-'  '-'  '-'   Copyright (C) 2002-2006 Judd Vinet
>   '--'
>                         This program may be freely redistributed under
>                         the terms of the GNU General Public License.
> 
> What am I doing wrong, to prevent update to pacman501?