branches/zip: ha_innobase::add_index(): Always commit prebuilt->trx,

also when row_merge_create_temporary_table() fails.  Otherwise, an
assertion would fail when the client connection is closed, because
prebuilt->trx would still be holding a table lock on innodb_table.

handler/handler0alter.cc

@@ -653,6 +653,7 @@ err_exit:
 		mem_heap_free(heap);
 		trx_general_rollback_for_mysql(trx, FALSE, NULL);
 		trx_free_for_mysql(trx);
+		trx_commit_for_mysql(prebuilt->trx);
 		DBUG_RETURN(error);
 	}