[FIX] account: invoice should be stored the first it is printed

addons/account/views/account_report.xml

@@ -9,6 +9,7 @@
             report_type="qweb-pdf"
             name="account.report_invoice"
             file="account.report_invoice"
+            attachment="(object.state in ('open','paid')) and ('INV'+(object.number or '').replace('/','')+'.pdf')"
         />
 
         <record id="account_invoices" model="ir.actions.report.xml">