dump_cache strange format for PTR

[Stephane Bortzmeyer]

I run 'unbound-control dump_cache' and I get, among other things:

70.168.69.4.in-addr.arpa.	86252	IN	PTR	ae-2-70.edge3.Paris1.Level3.net.

msg 108.7.134.192.in-addr.arpa. IN PTR 32896 1 86250 3 1 1 0
108.7.134.192.in-addr.arpa. IN PTR 0

Why two different formats for these two IP addresses (and the second
one seems difficult to parse...)? Using dig gives
reasonable results:

% dig PTR 108.7.134.192.in-addr.arpa.          

; <<>> DiG 9.10.3-P4-Debian <<>> PTR 108.7.134.192.in-addr.arpa.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27699
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
;; QUESTION SECTION:
;108.7.134.192.in-addr.arpa. IN PTR

;; ANSWER SECTION:
108.7.134.192.in-addr.arpa. 172498 IN PTR mx80-1-sqy.interco.nic.fr.

;; AUTHORITY SECTION:
7.134.192.in-addr.arpa.	172498 IN NS ns1.nic.fr.
7.134.192.in-addr.arpa.	172498 IN NS ns2.nic.fr.
7.134.192.in-addr.arpa.	172498 IN NS ns3.nic.fr.

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Sep 16 17:23:25 CEST 2016
;; MSG SIZE  rcvd: 148

 dig PTR 70.168.69.4.in-addr.arpa.

; <<>> DiG 9.10.3-P4-Debian <<>> PTR 70.168.69.4.in-addr.arpa.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22322
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
;; QUESTION SECTION:
;70.168.69.4.in-addr.arpa. IN PTR

;; ANSWER SECTION:
70.168.69.4.in-addr.arpa. 86089	IN PTR ae-2-70.edge3.Paris1.Level3.net.

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Sep 16 17:23:36 CEST 2016
;; MSG SIZE  rcvd: 98

Version 1.5.9
linked libs: libevent 2.0.21-stable (it uses epoll), OpenSSL 1.0.2h  3 May 2016
linked modules: dns64 python validator iterator