'emerge -uvDN world' fails with: root@wildcat:/root(26)# emerge -puvDN world ... [ebuild UD ] net-libs/webkit-gtk-1.8.3-r300:3 [1.10.2-r300:3] USE="doc%* geoloc gstreamer introspection jit spell webgl (-aqua) -coverage -debug {-test} -webkit2%" 0 kB ... !!! Multiple package instances within a single package slot have been pulled !!! into the dependency graph, resulting in a slot conflict: ... net-libs/webkit-gtk:3 (net-libs/webkit-gtk-1.8.3-r300::gentoo, ebuild scheduled for merge) pulled in by <net-libs/webkit-gtk-1.10:3[introspection] required by (media-sound/rhythmbox-2.97::gentoo, installed) (and 1 more with the same problem) (net-libs/webkit-gtk-1.10.2-r300::gentoo, installed) pulled in by >=net-libs/webkit-gtk-1.9.6:3[jit?,introspection?] required by (www-client/epiphany-3.6.1::gentoo, installed)
If you don't want rhythmbox crashing, you cannot have rb with gnome 3.6 components since they use different gstreamer slots. You can get around this by using USE="-cdr -html -webkit" until there is a gst-1.0 compatible rhythmbox release.
*** Bug 454194 has been marked as a duplicate of this bug. ***
