Incorrect diagnostic on 2136 of a zone in BIND back-end

[jpmens]

Latest master configured with:

launch=bind
master=yes
slave=yes
bind-dnssec-db=/etc/powerdns/bind/dnssec.db
bind-config=/etc/powerdns/bind/named.conf
bind-check-interval=60
experimental-dnsupdate=yes
allow-dnsupdate-from=127.0.0.1

# named.conf
zone "example.aa" IN {
        type master;
        file "/etc/powerdns/bind/example.aa";
};

$TTL 60
@       IN      SOA     localhost. root.localhost.  (
                                1               ; serial
                                3H              ; refresh
                                1H              ; retry
                                1W              ; expiry
                                1H )            ; minimum
        IN      NS      localhost.

        IN      A       127.0.0.1
www     IN      A       192.168.1.20

nsupdate <<!
server 127.0.0.1 53
zone example.aa
update add new.example.aa 86400 A 172.16.1.1
send
!

When running the nsupdate, PowerDNS logs out-of-zone data; I would have expected something along the lines of this back-end doesn't support updates:

UPDATE (55882) from 127.0.0.1 for example.aa: Processing started.
UPDATE (55882) from 127.0.0.1 for example.aa: starting transaction.
UPDATE (55882) from 127.0.0.1 for example.aa: Adding record new.example.aa|A
UPDATE (55882) from 127.0.0.1 for example.aa: Caught DBException: out-of-zone data 'new.example.aa' during AXFR of zone ''; Sending ServFail!

[pieterlexis]

2400