7/12/2013 2:04:40 PM
fail a payment before making sure there is something to pay.
This fixes payment error events associated with $0 invoices for accounts without
a default payment method.
* Fix test in beatrix which was now expecting an extra payment error event
* In PaymentProcessor, we need to handle external payment methods separately, to
avoid a potential deadlock
Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>