Something in trusted_server_facts is failing Puppet 4.0.0 Gem

[glennsarti]

The puppetlabs-puppet_agent module has recently started failing (in spectacular fashion) since rspec-puppet 2.6.10 was released. The Puppet Gem ~> 4.0.0 cell is now failing. Last known good run was using rspec-puppet 2.6.9

Failed run -https://travis-ci.org/puppetlabs/puppetlabs-puppet_agent/jobs/352629851
Last known good - https://travis-ci.org/puppetlabs/puppetlabs-puppet_agent/jobs/348013913

Note they're both using the same hash

Error seems to be related to;

1.1) �[31mFailure/Error:�[0m
          �[31m  �[0mraise �[1;34;4mArgumentError�[0m,�[0m
          �[31m    �[0m�[31m�[1;31m"�[0m�[31mAttempt to assign a value to unknown setting #{name.inspect}�[0m�[31m�[1;31m"�[0m�[31m�[0m�[0m
          �[31m�[0m
          �[31mArgumentError:�[0m
          �[31m  Attempt to assign a value to unknown setting :trusted_server_facts�[0m
          �[36m# ./vendor/bundle/ruby/2.1.0/gems/puppet-4.0.0/lib/puppet/settings.rb:1311:in `set'�[0m
          �[36m# ./vendor/bundle/ruby/2.1.0/gems/puppet-4.0.0/lib/puppet/settings.rb:333:in `block in initialize_app_defaults'�[0m
          �[36m# ./vendor/bundle/ruby/2.1.0/gems/puppet-4.0.0/lib/puppet/settings.rb:329:in `each'�[0m
          �[36m# ./vendor/bundle/ruby/2.1.0/gems/puppet-4.0.0/lib/puppet/settings.rb:329:in `initialize_app_defaults'�[0m
          �[36m# ./vendor/bundle/ruby/2.1.0/gems/rspec-puppet-2.6.11/lib/rspec-puppet/adapters.rb:52:in `setup_puppet'�[0m
          �[36m# ./vendor/bundle/ruby/2.1.0/gems/rspec-puppet-2.6.11/lib/rspec-puppet/adapters.rb:111:in `setup_puppet'�[0m
          �[36m# ./vendor/bundle/ruby/2.1.0/gems/rspec-puppet-2.6.11/lib/rspec-puppet.rb:114:in `block (2 levels) in <top (required)>'�[0m

Ignore the colour codes.

I've manually verified on a docker image that 2.6.9 works and 2.6.10 throws the same error.

Repro instructions

• Clone the repro
• Checkout master or 1.x branch (both heads are the same as of creation of this issue)
• Use Ruby 2.1.x
• Bundle install (note the rspec-puppet version)
• run bundle exec rake spec