app-emulation/xen-tools depends on <dev-libs/yajl-2 even though support for YAJL 2.x is present in Xen 4.2. It appears this restriction was added via bug #386461 but this is no longer necessary. Please update the dependency.
I agree. It's look like patches necessary for yajl-2 support were included sometimes in spring 2012!
ah right. Good pickup 22 Feb 2013; Ian Delaney <idella4@gentoo.org> xen-tools-4.2.0-r3.ebuild, xen-tools-4.2.1-r1.ebuild: Update the dependency yajl to current version, thx to 'BT' from Bug #458576