With cb80286a4ac22b9c55ee3d213d980ea73b11cd14, the helper function stringify_ansible_playbook_command was also applied on the `raw_arguments` content, which is not wanted. Given that users have used the `raw_arguments` option as a workaround to avoid the bug GH-6726, this new change ensure that any `--extra-vars` option passed as a raw argument won't be additonally enquoted by the ansible_local provisioner. This change also improves the ansible remote provisioner verbose output, but has no impact on its behaviour, which was already correct. Note that this refactoring introduces some code duplications that are not very elegant (see ansible_playbook_command_for_shell_execution in host.rb and execute_ansible_playbook_from_host in base.rb). I hope we can find a better implementation later, but it is good enough for now since all these parts are covered by corresponding unit tests (the `ansible_local` stuff being tested via the verbose output of the ansible remote provisioner).
Vagrant Core Plugins
These are plugins that ship with Vagrant. Vagrant core uses its own plugin system to power a lot of the core pieces that ship with Vagrant. Each plugin will have its own README which explains its specific role.