AccountingTransactionModule_createRelatedPaymentTransactionList:

  Refuse to create payment if payment creation is already in progress.
Invoice_createRelatedPaymentTransaction:
  Make sure we don't create an empty transaction.



git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@12876 20353a03-c40f-0410-a6d1-a30d3c3de9de