Guessnet doesn't work without any debug output

I just did a fresh install of ubuntu 13.10 and copied a previously working configuration of /etc/interfaces from my old system (ubuntu 11.04) to my new system.

The config (/etc/interfaces) looks like this

auto lo
iface lo inet loopback

#use guessnett
mapping eth0
        script /usr/sbin/guessnet-ifupdown
        map timeout: 3
        map default: none

iface home inet static
address 192.168.1.80
netmask 255.255.255.0
gateway 192.168.1.1
dns-nameservers 192.168.1.1

iface none inet dhcp

iface nocable inet manual
        test missing-cable

ifplugd is installed but if I plugin a LAN cable nothing happens.

Doing (everything as root) ifup eth0=home works as expected. If I try to execute guessnet manually by /usr/sbin/guessnet-ifupdown eth0 nothing happens, the program just runs without any output. Adding the --debug option just gives me

/usr/sbin/guessnet-ifupdown --debug eth0
guessnet: program name is guessnet-ifupdown: enabling ifupdown mode

Then it seems to sleep again.

Any idea how to fix this?

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: guessnet 0.55
ProcVersionSignature: Ubuntu 3.11.0-12.19-generic 3.11.3
Uname: Linux 3.11.0-12-generic x86_64
ApportVersion: 2.12.5-0ubuntu2
Architecture: amd64
Date: Sat Nov 23 09:07:18 2013
InstallationDate: Installed on 2013-11-22 (0 days ago)
InstallationMedia: Lubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MarkForUpload: True
SourcePackage: guessnet
UpgradeStatus: No upgrade log present (probably fresh install)