Strange problem: some subzones are loaded, some are not

[Stephane Bortzmeyer]

We have a strange problem on our nsd secondary nameserver (the BIND9
one is OK).

We have many subzones of ".fr" for the "notaires" (notaries?). Some
work, some not.

You can test it yourself on ns2.nic.fr. "paris.notaires.fr" or
"rhone.notaires.fr" work (you can query the SOA, you can ask
subdomains and you get a NXDOMAIN is they do not exist),
"aisne.notaires.fr" or "gironde.notaires.fr" does not work (you do not
get a SOA, you do not get an authoritative reply when querying a
subdomain).

In the nsd.zones, they are identical:

zone aisne.notaires.fr  secondary/aisne.notaires.fr  masters 192.93.0.1
zone gironde.notaires.fr  secondary/gironde.notaires.fr  masters 192.93.0.1
zone paris.notaires.fr  secondary/paris.notaires.fr  masters 192.93.0.1
zone rhone.notaires.fr  secondary/rhone.notaires.fr  masters 192.93.0.1

And the zone transfer was fine, all the files in secondary/ look OK. 

Any idea? A strange merging of data with the parent zone (ns2.nic.fr
is also authoritative for notaires.fr and fr).

nsd 1.2.2
Alpha + Tru 64 5.1B