Hello,
I still reproduce thus bug with last nagios2-common package:
# apt-cache policy nagios2-common
nagios2-common:
Installé : 2.9-1
Candidat : 2.9-1
Table de version :
*** 2.9-1 0
500 http://debian.mirror.inra.fr sid/main Packages
100 /var/lib/dpkg/status
Yann