HashiCorp has released a 2.1.4 update to Vagrant -- beware that this
version changes the order of plugin loading in a way that breaks on
MediaWiki-Vagrant's configuration file.
It should be fixable on our end, but for now either stick with the version
of Vagrant you have installed, or downgrade back to 2.1.2 if you already
updated.
https://phabricator.wikimedia.org/T203289
-- brion