squid-deb-proxy can fail because backports aren't added yet
On my local vagrant mx1 node, the way puppet decided to install squid-deb-proxy was to attempt it before the wheezy-backports sources were added, this results in this error:
- [mx1] err: /Stage[main]/Squid_deb_proxy::Client/Package[squid-deb-proxy-client]/ensure: change from purged to present failed: Execution of '/usr/bin/apt-get -q -y -o DPkg::Options::=--force-confold install squid-deb-proxy-client' returned 100: Reading package lists... - [mx1] Building dependency tree... - [mx1] Reading state information... - [mx1] E: Unable to locate package squid-deb-proxy-client
(from redmine: created on 2013-08-20, closed on 2013-09-05, relates #2988)