That is the problem mentioned by Nagy there (with suggestions for fixing it) :
http://www.archlinux.org/pipermail/pacman-dev/2007-August/009082.html
If a dependency conflicts with a local package and has to replace it,
the PM_SYNC_TYPE_DEPEND information is lost, and the resulting install
reason is wrong (the package is marked as explictly installed).
Signed-off-by: Chantry Xavier <shiningxc@gmail.com>