[BSA-089] Security update for nbd

Wouter Verhelst uploaded new packages for nbd which fixed the
following security problems:

CVE-2013-6410
Incorrect parsing of the access control lists

For the squeeze-backports distribution the problem has been fixed in
version 1:3.2-4~deb7u4~bpo60+1

nbd is not present in any other backports repository.

This end should point toward the ground if you want to go to space.

If it starts pointing toward space you are having a bad problem and you
will not go to space today.

– http://xkcd.com/1133/