diff -r f9ff7d1399d1 stock.py
--- a/trytond/trytond/modules/sale/stock.py	Fri Sep 04 16:30:54 2015 +0200
+++ b/trytond/trytond/modules/sale/stock.py	Fri Sep 04 16:31:35 2015 +0200
@@ -1,5 +1,6 @@
 #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 itertools import ifilter
 from sql.operators import Concat

 from trytond.model import Workflow, ModelView, fields
@@ -60,6 +61,35 @@

         return super(ShipmentOut, cls).draft(shipments)

+    def get_origins(self, name):
+        return ', '.join(set(ifilter(None, (m.origin_name
+                        for m in self.outgoing_moves))))
+
+    @classmethod
+    def _sync_inventory_to_outgoing_grouping_key(cls, move, type):
+        pool = Pool()
+        Move = pool.get('stock.move')
+        key = super(ShipmentOut,
+            cls)._sync_inventory_to_outgoing_grouping_key(move, type)
+        if type == 'outgoing':
+            key = tuple([key, move.origin])
+        if (type == 'inventory' and move.origin and
+                isinstance(move.origin, Move)):
+            key = tuple([key, move.origin.origin])
+        return key
+
+    def _get_outgoing_move(self, move):
+        new_move = super(ShipmentOut, self)._get_outgoing_move(move)
+        if new_move:
+            new_move.origin = move
+        return new_move
+
+    def _get_inventory_move(self, move):
+        new_move = super(ShipmentOut, self)._get_inventory_move(move)
+        if new_move:
+            new_move.origin = move
+        return new_move
+

 class ShipmentOutReturn:
     __name__ = 'stock.shipment.out.return'
@@ -146,6 +176,7 @@
     @classmethod
     def _get_origin(cls):
         models = super(Move, cls)._get_origin()
+        models.append('stock.move')
         models.append('sale.line')
         return models

diff -r f9ff7d1399d1 tests/scenario_sale.rst
--- a/trytond/trytond/modules/sale/tests/scenario_sale.rst	Fri Sep 04 16:30:54 2015 +0200
+++ b/trytond/trytond/modules/sale/tests/scenario_sale.rst	Fri Sep 04 16:31:35 2015 +0200
@@ -771,3 +771,57 @@
     5.0
     >>> stock_move.state
     u'draft'
+
+Create a sale with the same products with diferent price to be invoiced on
+shipment and check correctly invoiced::
+
+    >>> sale = Sale()
+    >>> sale.party = customer
+    >>> sale.payment_term = payment_term
+    >>> sale.invoice_method = 'shipment'
+    >>> line = sale.lines.new()
+    >>> line.product = product
+    >>> line.quantity = 10.0
+    >>> line = sale.lines.new()
+    >>> line.product = product
+    >>> line.quantity = 10.0
+    >>> line.unit_price = Decimal('9.0000')
+    >>> sale.click('quote')
+    >>> sale.click('confirm')
+    >>> sale.click('process')
+    >>> shipment, = sale.shipments
+    >>> config.user = stock_user.id
+    >>> for move in shipment.inventory_moves:
+    ...     move.quantity = 5.0
+    >>> shipment.click('assign_try')
+    True
+    >>> shipment.click('pack')
+    >>> shipment.click('done')
+    >>> config.user = sale_user.id
+    >>> sale.reload()
+    >>> invoice, = sale.invoices
+    >>> _, shipment, = sale.shipments
+    >>> invoice.untaxed_amount
+    Decimal('95.00')
+    >>> first_line, second_line = sorted(invoice.lines,
+    ...     key=lambda a: a.unit_price)
+    >>> first_line.unit_price
+    Decimal('9.0000')
+    >>> second_line.unit_price
+    Decimal('10.0000')
+    >>> config.user = stock_user.id
+    >>> shipment.click('assign_try')
+    True
+    >>> shipment.click('pack')
+    >>> shipment.click('done')
+    >>> config.user = sale_user.id
+    >>> sale.reload()
+    >>> _, invoice = sale.invoices
+    >>> invoice.untaxed_amount
+    Decimal('95.00')
+    >>> first_line, second_line = sorted(invoice.lines,
+    ...     key=lambda a: a.unit_price)
+    >>> first_line.unit_price
+    Decimal('9.0000')
+    >>> second_line.unit_price
+    Decimal('10.0000')