perl ./mtr sys_vars.wsrep_on_basic

mysqltest: At line 20: query 'SELECT @@global.wsrep_on' failed: 1047: WSREP has not yet prepared node for application use

The result from queries just before the failure was:
< snip >
SELECT @@session.wsrep_on;
@@session.wsrep_on
0

# scope and valid values
SET @@global.wsrep_on=OFF;
SELECT @@global.wsrep_on;
@@global.wsrep_on
0
SET @@global.wsrep_on=ON;
SELECT @@global.wsrep_on;

More results from queries before failure can be found in /data/repo/git/10.1/mysql-test/var/log/wsrep_on_basic.log

10.1/sql/sql_parse.cc:1134: bool do_command(THD*): Assertion `thd->m_statement_psi == __null' failed.
150907  2:33:13 [ERROR] mysqld got signal 6 ;

#6  0x00007f1cf633e311 in *__GI___assert_fail (assertion=0x7f1cf95dcfa8 "thd->m_statement_psi == __null", file=<optimized out>, line=1134, function=0x7f1cf95df890 "bool do_command(THD*)") at assert.c:81
#7  0x00007f1cf8c778e6 in do_command (thd=0x7f1cef176070) at /home/elenst/git/10.1/sql/sql_parse.cc:1134
#8  0x00007f1cf8dac069 in do_handle_one_connection (thd_arg=0x7f1cef176070) at /home/elenst/git/10.1/sql/sql_connect.cc:1350
#9  0x00007f1cf8dabdba in handle_one_connection (arg=0x7f1cef176070) at /home/elenst/git/10.1/sql/sql_connect.cc:1262
#10 0x00007f1cf9375d2b in pfs_spawn_thread (arg=0x7f1cf5823d70) at /home/elenst/git/10.1/storage/perfschema/pfs.cc:1860
#11 0x00007f1cf8359b50 in start_thread (arg=<optimized out>) at pthread_create.c:304
#12 0x00007f1cf63ee95d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112