Comment 2 for bug 1622002

We do have code in the sanity check scripts to detect the new version of dnsmasq, so someone deploying it should see the error if they run it.

I would rather not revert just because the failure of running dhcp_release6 is caught, so doesn't cause any collateral damage. Previously we would call dhcp_release with an IPv6 address and fail just as miserably.