puppetlabs/puppet — pull request #528 by stschulte (2012-02-27 00:33:50+00:00)
Title: #1076: User Type: Show warning if an empty group is specified

If one specifies an empty string for the group property of the user type, puppet builds an incorrect usermod command.

Example taken from #1076

user { "pinky":
gid => "pinky",
ensure => present,
groups => ""
}

The correct way to remove all group membership is to use `groups => []` so we should guide the user in that direction.

The commit series also tries to clean up the user_spec.