if the leg is already destroyed, just kill the original request.

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@6541 d0543943-73ff-0310-b7d9-9358b9ac24b2

libs/sofia-sip/libsofia-sip-ua/nua/nua_session.c

@@ -1089,9 +1089,14 @@ int nua_invite_client_ack(nua_client_request_t *cr, tagi_t const *tags)
   char const *phrase = "OK", *reason = NULL;
   char const *invite_branch;
 
-  assert(ds->ds_leg);
   assert(cr->cr_orq);
 
+  if (!ds->ds_leg) {
+	  nta_outgoing_destroy(cr->cr_orq);
+	  return -1;
+  }
+
+
   msg = nta_outgoing_getrequest(cr->cr_orq);
   sip = sip_object(msg);
   if (!msg)