Since the latest version in portage several new versions were released. Currently version 5.99.4 is the actual one. Basically renaming the old ebuild for 4.0.16 works, but it fails to install the man page. This has to be generated with "make doc" before which requires a command docbook2man. So probably the new ebuild should use the "doc" USE flag and depend on the package which provides this command then. Reproducible: Always
Using this myself now, and 5.99.15 is out.
6.0.0 has been released.
Bumped to 6.0.0. I dropped man-page installation as the conversion process with docbook2man failed.