woothemes/woocommerce — pull request #2264 by krbvroc1 (2013-01-21 15:18:13+00:00)
Title: Issue 1950

Your changes to Issue 1950 were not really complete. To be consistent with the
other changes you made, $checkout should also be passed to
woocommerce_before_checkout_form and woocommerce_after_checkout_form. That was actually 1/2 the point of the issue. I did not remove the $checkout that you are passing to
woocommerce_before_checkout_billing_form or woocommerce_after_checkout_billing_form, however, they are not needed or useful for Issue 1950. If you wish, I could remove them.

See
https://github.com/woothemes/woocommerce/issues/1950#issuecomment-12049990