[FIX] stock: unlink scrap

Forbids to unlink a done scrap.

opw-746294

addons/stock/i18n/stock.pot

@@ -6566,7 +6566,13 @@ msgid "You cannot cancel a stock move that has been set to 'Done'."
 msgstr ""
 
 #. module: stock
-#: code:addons/stock/models/stock_inventory.py:352
+#: code:addons/stock/models/stock_scrap.py:72
+#, python-format
+msgid "You cannot delete a scrap which is done."
+msgstr ""
+
+#. module: stock
+#: code:addons/stock/models/stock_inventory.py:374
 #, python-format
 msgid "You cannot have two inventory adjustements in state 'in Progess' with the same product(%s), same location(%s), same package, same owner and same lot. Please first validatethe first inventory adjustement with this product before creating another one."
 msgstr ""

addons/stock/models/stock_scrap.py

@@ -66,6 +66,12 @@ class StockScrap(models.Model):
         scrap.do_scrap()
         return scrap
 
+    @api.multi
+    def unlink(self):
+        if 'done' in self.mapped('state'):
+            raise UserError(_('You cannot delete a scrap which is done.'))
+        return super(StockScrap, self).unlink()
+
     def _get_origin_moves(self):
         return self.picking_id and self.picking_id.move_lines.filtered(lambda x: x.product_id == self.product_id)