The backports are now fully integrated with the main archive.
See:
https://labs.riseup.net/code/issues/4270
https://lists.debian.org/debian-devel-announce/2013/03/msg00007.html
$use_next_release = false
$debian_url = 'http://http.debian.net/debian/'
$security_url = 'http://security.debian.org/'
- $backports_url = 'http://backports.debian.org/debian-backports/'
+ $backports_url = $::lsbdistcodename ? {
+ 'wheezy' => $debian_url,
+ default => 'http://backports.debian.org/debian-backports/',
+ }
$volatile_url = 'http://volatile.debian.org/debian-volatile/'
$ubuntu_url = 'http://archive.ubuntu.com/ubuntu'
$repos = 'auto'