With PXC56 release binary, I could reproduce it. 

With codership-5.6 UNIV_DEBUG binary I got 

mysqld: /media/Tintin/Work/code/codership/codership-5.6/sql/binlog.cc:1181: int binlog_cache_data::finalize(THD*, Log_event*): Assertion `!flags.finalized' failed.
09:09:18 UTC - mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
We will try our best to scrape up some info that will hopefully help
diagnose the problem, but since we have already crashed,
something is definitely wrong and this may fail.

key_buffer_size=8388608
read_buffer_size=131072
max_used_connections=4
max_threads=151
thread_count=4
connection_count=4
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 68318 K  bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x2a392f0
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 7f797c077e48 thread_stack 0x40000
/chip/bin/mysqld(my_print_stacktrace+0x2c)[0x936e5a]
/chip/bin/mysqld(handle_fatal_signal+0x2f7)[0x66da3f]
/usr/lib/libpthread.so.0(+0xf880)[0x7f79a928a880]
/usr/lib/libc.so.6(gsignal+0x39)[0x7f79a7822389]
/usr/lib/libc.so.6(abort+0x148)[0x7f79a7823788]
/usr/lib/libc.so.6(+0x2e4a6)[0x7f79a781b4a6]
/usr/lib/libc.so.6(+0x2e552)[0x7f79a781b552]
/chip/bin/mysqld(_ZN17binlog_cache_data8finalizeEP3THDP9Log_event+0xdd)[0x8ccb6d]
/chip/bin/mysqld(_ZN22binlog_stmt_cache_data8finalizeEP3THD+0x7a)[0x8ccd04]
/chip/bin/mysqld(_ZN13MYSQL_BIN_LOG6commitEP3THDb+0x385)[0x8dfce5]
/chip/bin/mysqld(_Z23wsrep_thd_binlog_commitP3THDb+0x4a)[0x8e035b]
/chip/bin/mysqld(_ZN12TC_LOG_DUMMY6commitEP3THDb+0xf)[0x65d68d]
/chip/bin/mysqld(_Z15ha_commit_transP3THDbb+0x4e5)[0x5a7dcf]
/chip/bin/mysqld(_Z17trans_commit_stmtP3THD+0x475)[0x79bde1]
/chip/bin/mysqld(_Z21mysql_execute_commandP3THD+0x76f1)[0x7007dd]
/chip/bin/mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x4e8)[0x701ddd]
/chip/bin/mysqld[0x702761]
/chip/bin/mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x132d)[0x704005]
/chip/bin/mysqld(_Z10do_commandP3THD+0x716)[0x7067a1]
/chip/bin/mysqld(_Z24do_handle_one_connectionP3THD+0x143)[0x6c9738]
/chip/bin/mysqld(handle_one_connection+0x40)[0x6c98c3]
/chip/bin/mysqld(pfs_spawn_thread+0x14e)[0xc22de8]
/usr/lib/libpthread.so.0(+0x80a2)[0x7f79a92830a2]
/usr/lib/libc.so.6(clone+0x6d)[0x7f79a78d2d1d]

Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (7f7930004fd0): is an invalid pointer
Connection ID (thread ID): 5
Status: NOT_KILLED

The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains
information that should help you find out what is causing the crash.
            

Config used:
 [mysqld]
 socket = /chip/datadir/pxc.sock
 port = 40000
 basedir=/chip
 datadir=/chip/datadir

 binlog_format           = ROW
 innodb_buffer_pool_size         = 500M
 innodb_flush_log_at_trx_commit  = 0
 innodb_flush_method             = O_DIRECT
 wsrep_node_address=127.0.0.1
 innodb_log_files_in_group       = 2
 innodb_log_file_size            = 20M
 innodb_file_per_table           = 1

 wsrep_sst_receive_address=127.0.0.1:40001
 wsrep_node_incoming_address=127.0.0.1
 wsrep_cluster_address='gcomm://127.0.0.1:50010,127.0.0.1:60010'
 wsrep_provider=/chip/lib/libgalera_smm.so
 wsrep_provider_options = "gmcast.listen_addr=tcp://127.0.0.1:40010"

 wsrep_slave_threads=2
 wsrep_cluster_name=Chip56
 wsrep_sst_method=rsync
 #wsrep_sst_method=xtrabackup-v2

 innodb_locks_unsafe_for_binlog=1
 innodb_autoinc_lock_mode=2

 query_cache_type=0
 query_cache_size=0

 [client]
 user=root
 password=test
 socket = /chip/datadir/pxc.sock

 [xtrabackup]
 parallel=4
 compress



Started as:
sudo /chip/bin/mysqld --defaults-file=/chip/etc/my.cnf.local --basedir=/chip --user=mysql     --wsrep-debug --wsrep-new-cluster


>>mysql --defaults-file=/chip/etc/my.cnf.local -u root -ptest test
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.6.15-debug MySQL Community Server (GPL), wsrep_25.2.r4039

Copyright (c) 2000, 2013, Oracle, Monty Program Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MySQL [test]> create table mem1(a int not null auto_increment primary key, b int null) engine=memory;
Query OK, 0 rows affected (0.01 sec)

MySQL [test]> insert into mem1(a) values (NULL);
Query OK, 1 row affected (0.00 sec)

MySQL [test]> insert into mem1(a) values (NULL);
ERROR 2013 (HY000): Lost connection to MySQL server during query
MySQL [test]> insert into mem1(a) values (NULL);
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/chip/datadir/pxc.sock' (111)
ERROR: Can't connect to the server