Cannot complete checkout if gift card pays for whole order

Problem/Motivation

If a gift card balance covers the entire order total then the payment pane is empty. However trying to proceed to the review step results in a validation error because the billing profile is not filled in.

Steps to reproduce

I have not tested this yet on an unmodified commerce site. It may be related to my site's templates or it may be a legitimate bug. Need to verify this is a reproduceable problem before continuing.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes