It's not an automatic fail, if some WAL records were created during test.

WAL could be created e.g. by checkpoints, or some background activity that
sets hint bits. Such activity might cause a failure, if a data file is
modified in the master, but the change has not been replayed in the standby
yet. But just because it can make our check to fail, doesn't mean we need
to treat it as an automatic failure. Keep the warning, but consider the test
as a success, if the check itself found nothing wrong.

contrib/gp_replica_check/gp_replica_check.c

@@ -524,7 +524,6 @@ gp_replica_check(PG_FUNCTION_ARGS)
 		ereport(WARNING,
 				(errmsg("results may not be correct"),
 				 errdetail("IO may have been performed during the check")));
-		PG_RETURN_BOOL(false);
 	}
 
 	PG_RETURN_BOOL(dir_equal);