puppetlabs/puppetlabs-apt — pull request #123 by ctrlaltdel (2013-06-03 10:03:34+00:00)
Title: Install required_packages before 'apt-get update'

This is necessary when required_packages contains GPG keys that are used for
authenticating other packages. Tested with package ubuntu-cloud-keyring which
is included in Ubuntu main and used by the Ubuntu Cloud Archive.

I think the same problem applies to other *-keyring packages as well.