Link stock moves with invoice lines only for the same quantity sign as the order line

When invoice lines are created to correct invoices quantity, it should not be
linked to stock moves because it comes from a stock move being cancelled.

Closes #12972
(grafted from 20c538f39c871bacc0486b8506957229268f59cd)

--HG--
branch : 6.0

modules/purchase/purchase.py

@@ -1,6 +1,7 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
 import datetime
+import math
 from itertools import chain
 from decimal import Decimal
 
@@ -32,6 +33,10 @@ from trytond.modules.product import price_digits, round_price
 from .exceptions import PurchaseQuotationError, PartyLocationError
 
 
+def samesign(a, b):
+    return math.copysign(a, b) == a
+
+
 def get_shipments_returns(model_name):
     "Computes the returns or shipments"
     def method(self, name):
@@ -1585,7 +1590,8 @@ class Line(sequence_ordered(), ModelSQL, ModelView):
                     gettext('purchase'
                         '.msg_purchase_missing_account_expense',
                         purchase=self.purchase.rec_name))
-        invoice_line.stock_moves = self._get_invoice_line_moves()
+        if samesign(self.quantity, invoice_line.quantity):
+            invoice_line.stock_moves = self._get_invoice_line_moves()
         return [invoice_line]
 
     def _get_invoice_not_line(self):
@@ -1713,9 +1719,11 @@ class Line(sequence_ordered(), ModelSQL, ModelView):
     def _get_move_invoice_lines(self, move_type):
         'Return the invoice lines that should be shipped'
         if self.purchase.invoice_method == 'order':
-            return [l for l in self.invoice_lines]
+            lines = self.invoice_lines
         else:
-            return [l for l in self.invoice_lines if not l.stock_moves]
+            lines = filter(lambda l: not l.stock_moves, self.invoice_lines)
+        return list(filter(
+                lambda l: samesign(self.quantity, l.quantity), lines))
 
     def set_actual_quantity(self):
         pool = Pool()

modules/sale/sale.py

@@ -1,6 +1,7 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
 import datetime
+import math
 from decimal import Decimal
 from itertools import groupby, chain
 from functools import partial
@@ -29,6 +30,10 @@ from .exceptions import (
     SaleValidationError, SaleQuotationError, PartyLocationError)
 
 
+def samesign(a, b):
+    return math.copysign(a, b) == a
+
+
 def get_shipments_returns(model_name):
     "Computes the returns or shipments"
     def method(self, name):
@@ -1533,7 +1538,8 @@ class SaleLine(TaxableMixin, sequence_ordered(), ModelSQL, ModelView):
                 raise AccountError(
                     gettext('sale.msg_sale_missing_account_revenue',
                         sale=self.sale.rec_name))
-        invoice_line.stock_moves = self._get_invoice_line_moves()
+        if samesign(self.quantity, invoice_line.quantity):
+            invoice_line.stock_moves = self._get_invoice_line_moves()
         return [invoice_line]
 
     def _get_invoice_not_line(self):
@@ -1685,7 +1691,8 @@ class SaleLine(TaxableMixin, sequence_ordered(), ModelSQL, ModelView):
                         and invoice_line.invoice.state == 'paid'):
                     if invoice_line.moved_quantity < invoice_line.quantity:
                         invoice_lines.append(invoice_line)
-        return invoice_lines
+        return list(filter(
+                lambda l: samesign(self.quantity, l.quantity), invoice_lines))
 
     def set_actual_quantity(self):
         pool = Pool()