Heads up!
When WordPress 4.4 was released, deploys for lots of Trellis users broke because it required a WP-CLI update. This is also going to be the case with WordPress 4.5 when it’s released.
See http://wp-cli.org/blog/version-0.23.0.html
You can avoid any surprises now by upgrading to the new version. You can quickly upgrade WP-CLI on your remote servers by running:
sudo wget https://raw.githubusercontent.com/wp-cli/builds/gh-pages/phar/wp-cli.phar -O /usr/bin/wp
The preferred way to do it is to edit the WP-CLI role to reference the new version, then re-provision your server: