It's actually been out for several months now.
Created attachment 6334 [details] ebuild for cweb 3.64 This ebuild is a slight improvement over the last one, because it uses ${PV} in the SRC_URI. Woohoo.
From the CWEB homepage: "The authors do not intend to change CWEB henceforth unless some devastating new bug is discovered. Non-catastrophic infelicities should therefore be considered permanent _features_ of CWEB." Wow.
committed.