[FIX] purchase: unlink PO

A PO must be in state cancel to be canceled.
Before the fix, it was possible to cancel a draft PO
then if a PO linked to a procurement was deleted with being
canceled, the procurement stayed in running state.

opw:666311

addons/purchase/purchase.py

@@ -182,7 +182,7 @@ class PurchaseOrder(models.Model):
     @api.multi
     def unlink(self):
         for order in self:
-            if order.state not in ['draft', 'cancel']:
+            if not order.state == 'cancel':
                 raise UserError(_('In order to delete a purchase order, you must cancel it first.'))
         return super(PurchaseOrder, self).unlink()
 

addons/purchase/test/ui/delete_order.yml

@@ -13,15 +13,19 @@
         self.unlink(cr, uid, [ref("purchase_order_1")])
     except Exception,e:
         pass
+-
+  I delete a cancelled order.
+-
+  !python {model: purchase.order}: |
+    from openerp.exceptions import UserError
+    try:
+        self.unlink(cr, uid, [ref("purchase_order_7")])
+    except UserError:
+        pass
 -
   I delete a draft order.
 -
   !python {model: purchase.order}: |
     self.unlink(cr, uid, [ref("purchase_order_5")])
--
-  I delete a cancelled order.
--
-  !python {model: purchase.order}: |
-    self.unlink(cr, uid, [ref("purchase_order_7")])