Test sys_vars.innodb_buffer_pool_load_now_basic is unstable

[Laurynas Biveinis]

The test sys_vars.innodb_buffer_pool_load_now_basic is unstable even after bug 1625187 fix:

sys_vars.innodb_buffer_pool_load_now_basic w4 [ fail ]
        Test ended at 2016-12-29 08:13:49

CURRENT_TEST: sys_vars.innodb_buffer_pool_load_now_basic
mysqltest: At line 24: command "file_exists" failed with error 1. my_errno=175

The result from queries just before the failure was:
SET @orig = @@global.innodb_buffer_pool_load_now;
SELECT @orig;
@orig
0
SET GLOBAL innodb_buffer_pool_dump_now = ON;
safe_process[29944]: Child process: 29945, exit: 1

Server [mysqld.1 - pid: 29868, winpid: 29868] log:
Server log from this test:
----------SERVER LOG START-----------
2016-12-29 16:13:48 7f89947f9700 InnoDB: Dumping buffer pool(s) to .//ib_buffer_pool
2016-12-29 16:13:48 7f89947f9700 InnoDB: Buffer pool(s) dump completed at 161229 16:13:48
----------SERVER LOG END-------------

This is also https://jira.mariadb.org/browse/MDEV-9713. The fix would be to backport the following from 8.0:

commit f34e0a53e8c8cb909241638aef3f06b63b98a284
Author: Vasil Dimov <email address hidden>
Date: Tue Jul 14 11:27:20 2015 +0300

    Fix nondeterminism in a mtr test

[Laurynas Biveinis (laurynas-biveinis)]

     https://github.com/percona/percona-server/pull/1320
     https://github.com/percona/percona-server/pull/1321

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-2224