The data.tar.gz in the archive is not build correct. All file-paths must be relative, not absolute:
./usr/sbin/batmand-adv (at the moment) usr/sbin/batmand-adv (correct)
At the first look that doesn't seem to be a problem, but the packet-manager does not accept that. The files are on the box, but the manager thinks "not fully installed" and an "ipkg files batman-adv" leads to zero output.
Thanks in advance for fixing that 8-)
bye, Bastian Bittorf