When 16.04 LTS was released, PowerDNS had not yet reached a full 4.0.0 release; a pre-release version was included into xenial with the understanding that at some point an update would be made to a point release. I filed bug 1652392 to suggest that this should happen but of course have not found time myself to prepare packages for testing.
So I suggest rather than backporting this specific fix we should instead focus on updating 16.04 LTS to include an actual released version of PowerDNS.
When 16.04 LTS was released, PowerDNS had not yet reached a full 4.0.0 release; a pre-release version was included into xenial with the understanding that at some point an update would be made to a point release. I filed bug 1652392 to suggest that this should happen but of course have not found time myself to prepare packages for testing.
So I suggest rather than backporting this specific fix we should instead focus on updating 16.04 LTS to include an actual released version of PowerDNS.
Thanks