fix shutdown issue in test

src/exchange/test_taler_exchange_aggregator.c

@@ -340,11 +340,11 @@ maint_child_death (void *cls)
   aggregator_state->ioff++;
   state = aggregator_state;
   aggregator_state = NULL;
-  interpreter (state);
   child_death_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
                                                      pr,
                                                      &maint_child_death, NULL);
 
+  interpreter (state);
 }
 
 /**
@@ -1116,8 +1116,6 @@ run_test ()
 }
 
 
-
-
 /**
  * Main function that will be run by the scheduler.
  *