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

@@ -441,7 +441,21 @@ indexation_state::on_irreversible_block( uint32_t block_num ) {
 }
 
 void
-indexation_state::on_switch_fork( cached_data_t& cached_data, uint32_t block_num ) {
+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) + ")";
+          tx.exec( FORK_QUERY );
+          return data_processor::data_processing_status();
+      };
+      queries_commit_data_processor processor( _db_url, "Connect to the db", "connectdb", connect_to_the_db, nullptr, theApp );
+      processor.trigger( nullptr, 0 );
+      processor.join();
+      return;
+  }
+
   if ( _state != INDEXATION::P2P ) {
     return;
   }