Shopify/active_merchant — pull request #380 by shayfrendt (2012-06-18 20:00:07+00:00)
Title: Always pass CVV on card update for Braintree Blue

Always passing the CVV allows for "updating a credit card and explicitly
verifying the card" at the same time:
https://www.braintreepayments.com/docs/ruby/general/card_verification#credit_card_api