Voilà un exemple, un bug sur Curl, fais uniquement pour l'empêcher de passer en Testing (Sarge à l'heure actuelle) :

Reading package fields... Done
Reading package status... Done
Retrieving bug reports... Done       
grave bugs of curl (7.12.0.is.7.11.2-1 -> 7.12.0.rel-3) <open>
 #252785 - curl: fake bug to block curl from going into testing
Summary:
 curl(1 bug)
Are you sure to install/upgrade these packages? [Y/n/?/...]  ?
     y     - continue the apt installation.
     n     - stop the apt installation.
   <num>   - query the specified bug number (uses querybts).
     r     - redisplay bug lists.
 p <pkg..> - make pkgs pinned: need to restart apt to enable.
 p         - make all the above pkgs pinned. need to restart.
 i <num>   - make bug_number <num> ignored.
     ?     - print this help.
     w     - display bug lists in html (uses sensible-browser).
Are you sure to install/upgrade these packages? [Y/n/?/...]

Plus d'info sur le paquet :

23:58 xarli@iguzki ~$ sudo apt-cache show apt-listbugs
Package: apt-listbugs
Priority: optional
Section: admin
Installed-Size: 296
Maintainer: Masato Taruishi <taru@debian.org>
Architecture: all
Version: 0.0.40
Depends: ruby (>= 1.8), libdpkg-ruby1.8, apt, libzlib-ruby1.8, libintl-gettext-ruby1.8
Suggests: reportbug, debianutils (>= 2.0) | www-browser | w3m
Filename: pool/main/a/apt-listbugs/apt-listbugs_0.0.40_all.deb
Size: 64116
MD5sum: 9e9d1a5159aa938e7f3aa43e168fdc4e
Description: Lists critical bugs before each apt installation
 apt-listbugs is a tool which retrieves bug reports from the Debian
 Bug Tracking System and lists them. Especially, it is intended to
 be invoked before each upgrade/installation by apt in order to check
 whether the upgrade/installation is safe.
 .
 Most of Debian developers use the unstable version of Debian
 and some users also use it because the version is the latest
 snapshot which includes many new features and packages.
 .
 apt is a great convenient tool to follow your system to the latest
 version easily. On the other hand, the feature also makes your system
 break easily. If a package is broken and uploaded to the Debian unstable,
 the package will be installed on many Debian system soon.
 .
 This tool aims to make the broken upgrade as save as possible. You can
 check whether the upgrade is safe or not just before the upgrade.

23:58 xarli@iguzki ~$