Array concatenation, scoped variables and templates

gistfile1.pp

# Given the configuration below.
# Expected results list of users in bip.conf.
# Actual results in an empty file.

# bip.conf
<% 
usernames = scope.lookupvar('users::usernames')
fullnames = scope.lookupvar('users::fullnames')
-%>

<% usernames.each_with_index(username, index) do -%>
<%= username %>
<%= fullnames[index] %>
<% end -%>
# EOF bip.conf

# bip init.pp 
class bip {
  include users

  package { 'bip':
    ensure => latest,
  }

  file { 'bip.conf':
    ensure  => file,
    path    => '/etc/bip.conf',
    owner   => 'root',
    group   => 'bip',
    mode    => '0640',
    content =>  template('bip/bip.conf'),
    require => [Class['users'], Package['bip']],
  }
}
# EOF bip.pp

# irc.pp
define users::irc($key, $fullname, $ensure = 'present', $username = $title, $type = 'rsa') {
  include users
  $users::usernames += [$username]
  $users::fullnames += [$fullname]
  # etc...
# EOF irc.pp

# users init.pp
class users {
  $usernames = []
  $fullnames = []
# EOF users init.pp