[FIX] point_of_sale: traceback when printing invoice from POS

When we try to print an invoice from POS, this is cause by changing
method signature and that we cannot choos the report template anymore.

Refactoring in rev: e802380

addons/point_of_sale/report/pos_invoice.py

@@ -23,4 +23,4 @@ def get_report_values(self, docids, data=None):
             not_invoiced_orders_names = [a.name for a in not_invoiced_posorders]
             raise UserError(_('No link to an invoice for %s.') % ', '.join(not_invoiced_orders_names))
 
-        return self.env['ir.actions.report'].sudo().render_template('account.report_invoice', {'docs': self.env['account.invoice'].sudo().browse(ids_to_print)})
+        return {'docs': self.env['account.invoice'].sudo().browse(ids_to_print)}

addons/point_of_sale/views/point_of_sale_report.xml

@@ -25,4 +25,6 @@
         <field name="report_name">point_of_sale.report_saledetails</field>
     </record>
 
+    <template id="report_invoice" inherit_id="account.report_invoice" primary="True"/>
+
 </odoo>