when duplicate a sale, remove the shipment lines, to avoid duplication when process the new sale

sale.py

@@ -75,3 +75,12 @@ class SaleLine(metaclass=PoolMeta):
                 if tax_ids:
                     taxes.extend(tax_ids)
             self.taxes = taxes
+
+    @classmethod
+    def copy(cls, lines, default=None):
+        new_lines = []
+        for line in lines:
+            if line.shipment_cost != 0:
+                continue
+            new_lines.append(line)
+        return super(SaleLine, cls).copy(new_lines, default=default)