CiviMail: {action.*subscribeUrl} tokens replaced by empty strings over SMTP

The tokens

{action.unsubscribeUrl}

and

{action.resubscribeUrl}

can now be used in

{un,re}

subscribe confirmation templates. These tokens work properly if the confirmed actions were invoked over HTTP, but get replaced by empty strings if the actions were triggered by SMTP.

This is because over SMTP, the framework is set to SOAP, and CRM_Utils_System_Soap::url() returns null.