fix change of sequence on period for issue1170

(transplanted from cb1385d2b4487063f1c3565261e6f900a61d874a)

account.py

@@ -168,8 +168,8 @@ class Period(ModelSQL, ModelView):
                             period[sequence].id != \
                             vals[sequence]:
                         if invoice_obj.search(cursor, user, [
-                            ('date', '>=', period.start_date),
-                            ('date', '<=', period.end_date),
+                            ('invoice_date', '>=', period.start_date),
+                            ('invoice_date', '<=', period.end_date),
                             ('number', '!=', False),
                             ('type', '=', sequence[:-9]),
                             ], context=context):