(maint) Use UBUNTU_CODENAME rather than hardcoding xenial
(maint) Use UBUNTU_CODENAME rather than hardcoding xenial

puppetlabs/puppetserver,puppetlabs/puppet-server,puppetlabs/puppetserver,puppetlabs/puppet-server,puppetlabs/puppetserver,puppetlabs/puppetserver,puppetlabs/puppet-server