Summary and Info:
I've upgrade xorg stack with testing packages, now package fail upgrading on dependency failure, but the package is instaled !

Steps to Reproduce:
Install xorg/dri stuff from testing then:
[lordh@maison ~]$ LANG=C sudo pacman -Syu
:: Synchronizing package databases...
core is up to date
extra is up to date
testing is up to date
community is up to date
archlinuxfr is up to date
:: Starting full system upgrade...
warning: ati-dri: local (7.6-2) is newer than extra (7.5.1-2)
warning: binutils: local (2.20-1) is newer than core (2.19.1-5)
warning: fixesproto: local (4.1.1-1) is newer than extra (4.0-3)
warning: gcc: local (4.4.2-1) is newer than core (4.4.1-1)
warning: gcc-libs: local (4.4.2-1) is newer than core (4.4.1-1)
warning: glibc: local (2.10.1-5) is newer than core (2.10.1-4)
warning: inputproto: local (2.0-1) is newer than extra (1.5.1-2)
warning: kaffeine: local (1.0pre2-1) is newer than extra (0.8.8-1)
warning: kernel-headers: local (2.6.31.4-1) is newer than core (2.6.30.5-1)
warning: ktorrent: local (3.3beta1-1) is newer than extra (3.2.4-1)
warning: libdrm: local (2.4.15-1) is newer than extra (2.4.13-1)
warning: libgl: local (7.6-2) is newer than extra (7.5.1-2)
warning: libx11: local (1.3-1) is newer than extra (1.2.2-1)
warning: libxdamage: local (1.1.2-1) is newer than extra (1.1.1-2)
warning: libxext: local (1.1-1) is newer than extra (1.0.5-2)
warning: libxfixes: local (4.0.4-1) is newer than extra (4.0.3-2)
warning: libxfont: local (1.4.1-1) is newer than extra (1.4.0-1)
warning: libxfontcache: local (1.0.5-1) is newer than extra (1.0.4-2)
warning: libxt: local (1.0.7-1) is newer than extra (1.0.6-1)
warning: libxtst: local (1.1.0-1) is newer than extra (1.0.3-2)
warning: libxv: local (1.0.5-1) is newer than extra (1.0.4-1)
warning: libxxf86misc: local (1.0.2-1) is newer than extra (1.0.1-2)
warning: libxxf86vm: local (1.1.0-1) is newer than extra (1.0.99.1-1)
warning: mesa: local (7.6-2) is newer than extra (7.5.1-2)
warning: xextproto: local (7.1.1-1) is newer than extra (7.0.5-1)
warning: xf86-input-evdev: local (2.3.0-1) is newer than extra (2.2.5-1)
warning: xf86-video-ati: local (6.12.99.git20091014-1) is newer than extra (6.12.4-1)
warning: xf86-video-radeonhd: local (1.3.0-1) is newer than extra (1.2.5-1)
warning: xf86-video-vesa: local (2.2.1-1) is newer than extra (2.2.0-1)
warning: xorg-apps: local (7.5-2) is newer than extra (7.5-1.1)
warning: xorg-font-utils: local (7.5-1) is newer than extra (7.4-3)
warning: xorg-server: local (1.7.0.902-1) is newer than extra (1.6.3.901-1)
warning: xorg-utils: local (7.5-1) is newer than extra (7.4-4)
warning: xorg-xkb-utils: local (7.5-1) is newer than extra (7.4-2)
resolving dependencies...
looking for inter-conflicts...
error: failed to prepare transaction (could not satisfy dependencies)
:: libxtst: requires libxi>=1.3
[lordh@maison ~]$ LANG=C pacman -Q libxtst libxi
libxtst 1.1.0-1
libxi 1.3-1