Set background mining started bool to false on bg thread start. If mining::stop then mining::start, idle logic is re-run instead of starting immediately (if it was running before stop).

src/cryptonote_basic/miner.cpp

@@ -526,6 +526,7 @@ namespace cryptonote
     uint64_t prev_total_time, current_total_time;
     uint64_t prev_idle_time, current_idle_time;
     uint64_t previous_process_time = 0, current_process_time = 0;
+    m_is_background_mining_enabled = false;
 
     if(!get_system_times(prev_total_time, prev_idle_time))
     {