issue #223: correctly detect if reversible data have to be removed after hived restart

• now fork event is added only when hived wills end notification, no artificial event during 'hive.connect'
• hive.connect is always executed before on_reindex notification, before data are marked as dirty

src/sql_serializer/indexation_state.cpp

@@ -443,6 +443,7 @@ indexation_state::on_irreversible_block( uint32_t block_num ) {
 void
 indexation_state::on_switch_fork( uint32_t last_synced_block_num, cached_data_t& cached_data, uint32_t block_num ) {
   if ( _state == INDEXATION::START && last_synced_block_num > block_num ) {
+      ilog( "Fork at start ${lb} ${b}", ("lb", last_synced_block_num)("b", block_num) );
       // it is fork generated by hived during starting
       auto connect_to_the_db = [&](const data_processor::data_chunk_ptr& dataPtr, transaction_controllers::transaction& tx ){
           const auto FORK_QUERY = "SELECT hive.back_from_fork(" + std::to_string(block_num) + ")";