Set currency template variable from contribution pages

Set currency template variable from contribution pages

When we load the PaymentForm the currency is set there and assigned to the template.

However, if the form doesn't load by default (ie because there is no payment processor selected by
default) the currency variable is not assigned to the template.

When the payment form is loaded by
      var dataUrl = '{crmURL p='civicrm/payment/form' h=0 q=formName=