first commit

modules/account_rule/sale.py

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+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
+from trytond.pool import PoolMeta
+from trytond.transaction import Transaction
+
+
+class Line(metaclass=PoolMeta):
+    __name__ = 'sale.line'
+
+    def get_invoice_line(self):
+        with Transaction().set_context(
+                taxes=[t.id for t in self.taxes],
+                return_=self.type == 'line' and self.quantity < 0):
+            return super().get_invoice_line()