[FIX] sale: fix incorrect on_change on sale.order.line resetting the UoM field + added test

lp bug: https://launchpad.net/bugs/1082409 fixed

bzr revid: odo@openerp.com-20130131184356-y9ck1dr31nlsp73r

addons/sale/sale.py

@@ -926,7 +926,6 @@ class sale_order_line(osv.osv):
         elif uom: # whether uos is set or not
             default_uom = product_obj.uom_id and product_obj.uom_id.id
             q = product_uom_obj._compute_qty(cr, uid, uom, qty, default_uom)
-            result['product_uom'] = default_uom
             if product_obj.uos_id:
                 result['product_uos'] = product_obj.uos_id.id
                 result['product_uos_qty'] = qty * product_obj.uos_coeff

addons/sale/test/sale_order_demo.yml

@@ -14,3 +14,23 @@
   !assert {model: sale.order, id: sale.sale_order_test1, string: The onchange function of product was not correctly triggered}:
     - order_line[0].name == u'[LCD17] 17\u201d LCD Monitor'
     - order_line[0].price_unit == 1350.0
+    - order_line[0].product_uom_qty == 8
+    - order_line[0].product_uom.id == ref('product.product_uom_unit')
+
+-
+  I create another sale order
+-
+  !record {model: sale.order, id: sale_order_test2}:
+    partner_id: base.res_partner_2
+    order_line: 
+      - product_id: product.product_product_7
+        product_uom_qty: 16
+        product_uom: product.product_uom_dozen
+-
+  I verify that the onchange was correctly triggered
+-
+  !assert {model: sale.order, id: sale.sale_order_test2, string: The onchange function of product was not correctly triggered}:
+    - order_line[0].name == u'[LCD17] 17\u201d LCD Monitor'
+    - order_line[0].price_unit == 1350.0 * 12
+    - order_line[0].product_uom.id == ref('product.product_uom_dozen')
+    - order_line[0].product_uom_qty == 16