remove extra mark_as_cancelled method

src/shop/models.py

@@ -232,6 +232,7 @@ class Order(CreatedUpdatedModel):
             messages.error(request, "Order %s is paid, cannot cancel a paid order!" % self.pk)
         else:
             self.cancelled = True
+            self.open = None
             self.save()
 
     def is_not_handed_out(self):
@@ -264,11 +265,6 @@ class Order(CreatedUpdatedModel):
         else:
             return False
 
-    def mark_as_cancelled(self):
-        self.cancelled = True
-        self.open = None
-        self.save()
-
     @property
     def coinifyapiinvoice(self):
         if not self.coinify_api_invoices.exists():