Errors when attempting to modify recurring transactions after applying patch

I have applied 92799de1 as a patch (from issue #18 (closed)), and am now seeing new errors when attempting to update recurring transaction details.

When attempting to update transaction amount/installments:

Error: Call to undefined method CRM_Core_Payment_AuthNetCreditcard::beginChangeSubscriptionAmount() in CRM_Core_Payment_AuthorizeNetCommon->changeSubscriptionAmount() (line 571 of /var/www/web/public/civi/extensions/authnet/CRM/Core/Payment/AuthorizeNetCommon.php).

When attempting to update billing details:

Error: Call to undefined method CRM_Core_Payment_AuthNetCreditcard::beginUpdateSubscriptionBillingInfo() in CRM_Core_Payment_AuthorizeNetCommon->updateSubscriptionBillingInfo() (line 519 of /var/www/web/public/civi/extensions/authnet/CRM/Core/Payment/AuthorizeNetCommon.php).

AuthorizeNetCommon.php is the file that was changed in that above referenced commit, and lines 519 and 571 were included in the changes.