puppet resource user --to_yaml produces invalid yaml on solaris

Puppet Version: 2016.4.7
Puppet Server Version: 2016.4.7
OS Name/Version: Solaris 11

puppet resource user --to_yaml produces invalid yaml when user keys are set:

users:

  user:

    ensure: 'present'

    keys: {'lock_after_retries' => 'no'} 

Desired Behavior:

--to_yaml should produce valid yaml syntax

Actual Behavior:

yaml is invalid (according to yaml-lint and YAML.load