ipv6 nd rdnss feature not implemented?

From what I can make from quagga mailing lists the router advertisement feature was enhanced to allow DNS servers to be specified as per RFC5006 some time around release 0.99.13.

This does not appear to be supported by the version in the yakkity repository (1.0.20160315). Does anyone know if this an optional feature that's not been compiled or is it still in development, or if it should be working and I'm screwing up somewhere? :-)

In zebra.conf this should apparently work:

interface ens123
  ipv6 address 2001:etc
  no ipv6 nd suppress-ra
  ipv6 nd prefix 2001:etc:blah::/64
  ipv6 nd rdnss 2001:etc:blah::123

What actually happens is it errors with
*** Error reading config: There is no such command.
*** Error occured processing line 37, below:
 ipv6 nd rdnss 2001:etc:blah:123

I guess I'll be having a play with radvd and DHCPv6 in the mean time...

/R