Fix test to work with cost on quote

Since issue4531, the cost line is only created at quotation.

issue4655
review15301002

tests/scenario_carrier_percentage_with_purchase_shipment_cost.rst

@@ -162,14 +162,14 @@ Sale products with cost on shipment::
     >>> sale_line = sale.lines.new()
     >>> sale_line.product = product
     >>> sale_line.quantity = 5.0
+    >>> sale.click('quote')
     >>> cost_line = sale.lines[-1]
     >>> cost_line.product == carrier_product
     True
     >>> cost_line.quantity
-    1
+    1.0
     >>> cost_line.amount
     Decimal('15.00')
-    >>> sale.click('quote')
     >>> sale.click('confirm')
     >>> sale.click('process')
     >>> sale.state
@@ -223,6 +223,7 @@ Sale products with cost on order::
     >>> sale_line = sale.lines.new()
     >>> sale_line.product = product
     >>> sale_line.quantity = 3.0
+    >>> sale.click('quote')
     >>> cost_line = sale.lines[-1]
     >>> cost_line.product == carrier_product
     True
@@ -230,7 +231,6 @@ Sale products with cost on order::
     True
     >>> cost_line.amount
     Decimal('9.00')
-    >>> sale.click('quote')
     >>> sale.click('confirm')
     >>> sale.click('process')
     >>> sale.state