Really fix crashes now. Revert isis_circuit_update_params() part of previous
commit. Replace all if_is_up() calls with if_is_operative().
diff --git a/isisd/isis_circuit.c b/isisd/isis_circuit.c
index ca5befb..1a98a63 100644
--- a/isisd/isis_circuit.c
+++ b/isisd/isis_circuit.c
@@ -430,12 +430,7 @@
 isis_circuit_update_params (struct isis_circuit *circuit,
 			    struct interface *ifp)
 {
-  /* HT: It can happen at the moment during interface up event because we
-   * actually delete circuit during interface down event. Should be really
-   * cleaned up. TODO */
-  /* assert (circuit); */
-  if (!circuit)
-    return;
+  assert (circuit);
 
   if (circuit->circuit_id != ifp->ifindex)
     {