Bugzilla Bug 165118

artsplugin-mpg123-3.5.0 has MAXKDEVER=3.5.5 in the ebuild file. So it wants to
downgrade kdelibs-3.5.6 to kdelibs-3.5.5 and that conflicts with other
kde-3.5.6 packages.

Output of emerge -uDp world:
!!! Multiple versions within a single package slot have been
!!! pulled into the dependency graph:

('ebuild', '/', 'kde-base/kdelibs-3.5.5-r7', 'merge') pulled in by
  ('ebuild', '/', 'kde-base/artsplugin-mpg123-3.5.0', 'nomerge')

('ebuild', '/', 'kde-base/kdelibs-3.5.6-r2', 'merge') pulled in by
  ('ebuild', '/', 'kde-base/kuser-3.5.6', 'nomerge')
  (...)
  ('ebuild', '/', 'kde-base/kdemultimedia-arts-3.5.6', 'nomerge')

It may be possible to solve this problem by using package.mask to
prevent one of those packages from being selected. However, it is also
possible that conflicting dependencies exist such that they are
impossible to satisfy simultaneously. If such a conflict exists in the
dependencies of two different packages, then those packages can not be
installed simultaneously.

For more information, see MASKED PACKAGES section in the emerge man page
or refer to the Gentoo Handbook.

... done!
[ebuild     U ] kde-base/kdelibs-3.5.6-r2 [3.5.6-r1]
[ebuild     UD] kde-base/kdelibs-3.5.5-r7 [3.5.6-r1]

Reproducible: Always

Steps to Reproduce:
1. emerge -uDp world
2.
3.

Actual Results:  
failed merge

Expected Results:  
successful merge

emerge --info
Portage 2.1.2-r5 (default-linux/x86/2006.1/desktop, gcc-4.1.1, glibc-2.5-r0,
2.6.18-suspend2 i686)
=================================================================
System uname: 2.6.18-suspend2 i686 Intel(R) Pentium(R) 4 CPU 3.06GHz
Gentoo Base System release 1.12.9
Timestamp of tree: Sat, 03 Feb 2007 11:30:01 +0000
distcc 2.18.3 i686-pc-linux-gnu (protocols 1 and 2) (default port 3632)
[enabled]
ccache version 2.4 [enabled]
dev-java/java-config: 1.3.7, 2.0.31-r3
dev-lang/python:     2.3.6, 2.4.4
dev-python/pycrypto: 2.0.1-r5
dev-util/ccache:     2.4-r6
sys-apps/sandbox:    1.2.18.1
sys-devel/autoconf:  2.13, 2.61
sys-devel/automake:  1.4_p6, 1.5, 1.6.3, 1.7.9-r1, 1.8.5-r3, 1.9.6-r2, 1.10
sys-devel/binutils:  2.17
sys-devel/gcc-config: 1.3.14
sys-devel/libtool:   1.5.22
virtual/os-headers:  2.6.19.2-r2
ACCEPT_KEYWORDS="x86 ~x86"
AUTOCLEAN="yes"
CBUILD="i686-pc-linux-gnu"
CFLAGS="-Os -march=pentium4 -fomit-frame-pointer"
CHOST="i686-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/kde/3.5/env /usr/kde/3.5/share/config
/usr/kde/3.5/shutdown /usr/share/X11/xkb /usr/share/config"
CONFIG_PROTECT_MASK="/etc/env.d /etc/env.d/java/ /etc/gconf
/etc/java-config/vms/ /etc/revdep-rebuild /etc/splash /etc/terminfo
/etc/texmf/web2c"
CXXFLAGS="-Os -march=pentium4 -fomit-frame-pointer"
DISTDIR="/usr/portage/distfiles"
FEATURES="autoconfig candy ccache distcc distlocks metadata-transfer sandbox
sfperms strict"
GENTOO_MIRRORS="ftp://ftp.tu-clausthal.de/pub/linux/gentoo/
http://gentoo.inode.at/ ftp://linux.rz.ruhr-uni-bochum.de/gentoo-mirror/
ftp://ftp.uni-erlangen.de/pub/mirrors/gentoo
http://mirrors.sec.informatik.tu-darmstadt.de/gentoo/
ftp://ftp.gentoo.mesh-solutions.com/gentoo/"
LANG="de_DE@euro"
LC_ALL="de_DE.UTF-8"
LINGUAS="de"
MAKEOPTS="-j3"
PKGDIR="/usr/portage/packages"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress
--force --whole-file --delete --delete-after --stats --timeout=180
--exclude=/distfiles --exclude=/local --exclude=/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY="/usr/local/portage"
SYNC="rsync://rsync.gentoo.org/gentoo-portage"
USE="16bit 16bittmp 7zip X aac aalib acpi alsa amarok arts asf audacious berkdb
bitmap-fonts bluetooth bzip2 cairo cdda cddb cdparanoia cdr cli cpudetection
cracklib crypt css cups dbus directfb divx dlloader dri dvd dvdr dvdread eds
emboss encode esd fam fat fbcon fbsplash firefox flac font-server fortran gd
gdbm gif gimp gmedia gnokii gnome gnutls gpm gstreamer gtk gtk2 gtkhtml gzip
hal iconv icq id3 ieee1394 imagemagick irc irda isdnlog java jpeg kde
kdehiddenvisibility kdepim kdm lame ldap libg++ lirc logitech-mouse mad midi
mikmod mime mmx mozbranding mozdevelop mozilla mozsvg mp3 mp4 mpeg mpeg2
mplayer musepack ncurses nls nptl nptlonly nsplugin ntfs ntlm offensive ogg
opengl oss pam pcmcia pcre pdf perl player png posix ppds pppd python qt3
qt3support qt4 quicktime rar readline real reflection reiserfs rtc samba sdl
session smp spell spl sse sse2 ssl subtitles svg svga sysfs tcl tcltk tcpd
themes threads tidy tk truetype truetype-fonts type1 type1-fonts udev unicode
usb vcd vorbis wifi win32codecs wma wmf wmp wxwindows x264 x86 xine xml xorg
xosd xpm xprint xscreensaver xv xvid zip zlib" ALSA_CARDS="ali5451 als4000
atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968
fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx
via82xx-modem ymfpci" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop
empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mulaw multi
null plug rate route share shm softvol" ELIBC="glibc" INPUT_DEVICES="evdev
joystick keyboard mouse synaptics" KERNEL="linux" LCD_DEVICES="bayrad cfontz
cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="de"
USERLAND="GNU" VIDEO_CARDS="radeon"
Unset:  CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LDFLAGS,
PORTAGE_RSYNC_EXTRA_OPTS

Thanks, fixed by bumping to 3.5.6.