On Debian (and Ubuntu) you cannot get vdirsyncer to run with requests from the official repositories.

A simple solution is to install vdirsyncer in a virtualenv (tutorial) and than use vdirsyncer from that virtualenv via this script (assuming your virtualenv is called vdirsyncer as well):

#!/bin/sh
VIRTUALENV=vdirsyncer
. ~/.virtualenvs/$VIRTUALENV/bin/activate
~/.virtualenvs/$VIRTUALENV/bin/vdirsyncer $@