Please stabalise xen-sources-2.6.29-r4.ebuild and xen-sources-2.6.31-r10.ebuild . Both are over 30d old, and I could not find any closed bug against them.
.31 has been unmasked a few days ago, .29 a bit longer. Let the arch teams finish the general xen stabilization (with a patched .18) first ( #293714 ) and wait a while for them to settle down ...