According to the ebuild comment, dhcp-3.0.3-dhclient-dbus.patch is there to support NetworkManager. Current versions of NetworkManager (at least 0.9.x) have their own dhclient script that provides all the necessary communication. This patch is therefore obsolete and should be removed.
should be all set now in the tree; thanks for the report! Commit message: Drop NetworkManager dbus patch as NM handles this itself now http://sources.gentoo.org/net-misc/dhcp/dhcp-4.2.4_p2-r1.ebuild?r1=1.2&r2=1.3
Thanks!