Users of Ubuntu and Debian systems who use package promises to list the patches available on their system may experience a system stall since the generic package method defined for Debian does not set the non-interactive flag. This causes the package manager (aptitude will be used if it's installed on the host) to stop, requesting user input. This leads cf-agent to hang. As a work around, the standard library policy can be edited to ensure the package manager has the appropriate environment variable set to avoid this unwanted interaction.
To work around, navigate to /var/cfengine/masterfiles/lib/3.5 and open the policy file packages.cf
Look for this line (should be line 954): package_patch_list_command => "/usr/bin/aptitude --assume-yes --simulate --verbose full-upgrade";
and replace it with:
package_patch_list_command =>$(debian_knowledge.call_aptitude) --assume-yes --simulate --verbose full-upgrade";