The test suite in 0.997 will fail if either python or the kernel is missing ipv6 support. I've reported this upstream: http://www.corpit.ru/pipermail/rbldnsd/2013q3/001179.html Jeff Dairiki was kind enough to research and implement the fix, eliminating an odd bug in the process. IN_PROGRESS, please.
12 Dec 2013; Michael Orlitzky <mjo@gentoo.org> +files/confd-0.997a, +files/initd-0.997a, +files/rbldnsd-0.997a-robust-ipv6-test-support.patch, +rbldnsd-0.997a.ebuild: Version bump fixing bugs #485536 and #493354 in the process. Upstream has been quiet for a while, but I've tested the patch a good deal. So here it is.