slave.cc:

      BUG#20850: Assert during slave shutdown in many rpl_* tests
      This patch has already been applied to 5.1.

sql/slave.cc

@@ -3717,15 +3717,12 @@ log space");
   write_ignored_events_info_to_relay_log(thd, mi);
   thd->proc_info = "Waiting for slave mutex on exit";
   pthread_mutex_lock(&mi->run_lock);
-  mi->slave_running = 0;
-  mi->io_thd = 0;
 
   /* Forget the relay log's format */
   delete mi->rli.relay_log.description_event_for_queue;
   mi->rli.relay_log.description_event_for_queue= 0;
   // TODO: make rpl_status part of MASTER_INFO
   change_rpl_status(RPL_ACTIVE_SLAVE,RPL_IDLE_SLAVE);
-  mi->abort_slave = 0; // TODO: check if this is needed
   DBUG_ASSERT(thd->net.buff != 0);
   net_end(&thd->net); // destructor will not free it, because net.vio is 0
   close_thread_tables(thd, 0);
@@ -3733,8 +3730,11 @@ log space");
   THD_CHECK_SENTRY(thd);
   delete thd;
   pthread_mutex_unlock(&LOCK_thread_count);
-  pthread_cond_broadcast(&mi->stop_cond);	// tell the world we are done
+  mi->abort_slave= 0;
+  mi->slave_running= 0;
+  mi->io_thd= 0;
   pthread_mutex_unlock(&mi->run_lock);
+  pthread_cond_broadcast(&mi->stop_cond);       // tell the world we are done
 #ifndef DBUG_OFF
   if (abort_slave_event_count && !events_till_abort)
     goto slave_begin;