Addendum:
* Before calling THD::init_for_queries(), flip the current_thd to wsrep
thread so that memory gets allocated for the right THD.
* Use wsrep_creating_startup_threads instead of plugins_are_initialized
as the condition for the execution of THD::init_for_queries() within
start_wsrep_THD(), as use of latter could still leave some room for
race.

Problem:
When mysqld starts as a galera node, it creates 2 system threads
(applier & rollbacker) using start_wsrep_THD(). These threads are
created before plugin initialization (plugin_init()) for SST methods
like rsync and xtrabackup.

The threads' initialization itself can proceed in parallel to mysqld's
main thread of execution. As a result, the thread initialization code
(start_wsrep_THD()) can end up accessing some un/partially initialized
structures (like maria_hton, in this particular case) resulting in
segfault.

Solution:
Fixed by calling THD::init_for_queries() (which accesses maria_hton)
only after the plugins have been initialized.

* Merge fix for issue #127 from mysql-wsrep (commit : a0ba0d7)
* Also, cherry-picked a similar fix for OpenSUSE (commit : 7790cb1)

Add 'bootstrap' to debian init script.

* Also modified name regex to include '#' as a valid symbol for
tests under disabled.def.

Galera MTR Tests: fix typo in the galera_as_slave_nonprim test, in suite/galera/galera_3nodes_as_slave.cnf

- setting error code for slave, if mysql slave node dropped from cluster

- Galera related errors in mysql slave applying will now cause slave to
abort

Galera MTR Tests: Instruct xtrabackup SST's socat to use 1024-bit DH keys to avoid 'error:14082174:SSL routines:SSL3_CHECK_CERT_AND_ALGORITHM:dh key too small'

Galera MTR Tests: Tests for GRA*.log files, replication bundle, preordered events, forced binlog format

Galera MTR Tests: An end-to-end test with restoring a node from xtrabackup; a test for restoring the primary component via pc.bootstrap

Galera MTR Tests: mark all tests operating on large data sets with --source include/big-test.inc to help with Valgrind

Galera MTR Tests: Use SET GLOBAL when setting wsrep_replicate_myisam, as it is a GLOBAL variable in MySQL Galera Cluster and SESSION in Percona XTraDB Cluster

Before this, FLUSH TABLES and FLUSH TABLES t1 (REFRESH_TABLES hereafter) were executed locally,
which also had implications for GTID. MySQL async replication does
replicate FLUSH TABLES.

Hence, this commit

a)  Adds REFRESH_TABLES to TOI.

b) Skips LOCK-based REFRESH_TABLES from TOI, ie. FLUSH TABLES WITH READ
LOCK and FLUSH TABLES FOR EXPORT.

c) Executes them after reload_acl_and_cache. This is done since
reload_acl_and_cache checks for thd->locked_tables_mode and does upgrade
of MDL locks accordingly. A failure here means REFRESH_TABLES cannot
run.

    i) This is also important since LOCK TABLES is not replicated in
    galera.

d) Test galera_flush has been modified for

    i) wsrep_replicate_myisam SESSION variable.

    ii) Testing REFRESH_TABLES.

    iii) Testing REFRESH_TABLES + LOCK TABLES.

e) Use different WSREP_TO_ISOLATION_BEGIN for global FLUSH TABLES and FLUSH TABLES <table,>.