Seems to be still there as of r3840. Reproduced with heavy CPU-contending load (total 127 threads at the moment of crash).

Offending code:
    if (thd->mysys_var->current_cond)
    {
      mysql_mutex_lock(thd->mysys_var->current_mutex);
      mysql_cond_broadcast(thd->mysys_var->current_cond);
      mysql_mutex_unlock(thd->mysys_var->current_mutex);
    }

by the time mysql_mutex_unlock() is called both current_cond and current_mutex are 0x0.

Out of 8 wsrep slave threads 1 is applying writeset and other 7 are waiting fro commit.

Thread 2 (Thread 0x7fde783df700 (LWP 17210)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fde87b82fd5 in wait (cond=..., this=<optimized out>) at galerautils/src/gu_lock.hpp:56
#2  galera::Monitor<galera::ReplicatorSMM::CommitOrder>::enter (this=this@entry=0x295ed58, obj=...) at galera/src/monitor.hpp:126
#3  0x00007fde87b7c9d2 in galera::ReplicatorSMM::apply_trx (this=this@entry=0x295e2c0, recv_ctx=recv_ctx@entry=0x7fde40000990, trx=trx@entry=0x7fde40059990) at galera/src/replicator_smm.cpp:471

Thread 85 (Thread 0x7fde78524700 (LWP 17205)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fde87b82fd5 in wait (cond=..., this=<optimized out>) at galerautils/src/gu_lock.hpp:56
#2  galera::Monitor<galera::ReplicatorSMM::CommitOrder>::enter (this=this@entry=0x295ed58, obj=...) at galera/src/monitor.hpp:126
#3  0x00007fde87b7c9d2 in galera::ReplicatorSMM::apply_trx (this=this@entry=0x295e2c0, recv_ctx=recv_ctx@entry=0x7fde30000990, trx=trx@entry=0x7fde3002c790) at galera/src/replicator_smm.cpp:471

Thread 95 (Thread 0x7fde78461700 (LWP 17208)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fde87b82fd5 in wait (cond=..., this=<optimized out>) at galerautils/src/gu_lock.hpp:56
#2  galera::Monitor<galera::ReplicatorSMM::CommitOrder>::enter (this=this@entry=0x295ed58, obj=...) at galera/src/monitor.hpp:126
#3  0x00007fde87b7c9d2 in galera::ReplicatorSMM::apply_trx (this=this@entry=0x295e2c0, recv_ctx=recv_ctx@entry=0x7fde48000990, trx=trx@entry=0x7fde48224520) at galera/src/replicator_smm.cpp:471

Thread 97 (Thread 0x7fde784a2700 (LWP 17207)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fde87b82fd5 in wait (cond=..., this=<optimized out>) at galerautils/src/gu_lock.hpp:56
#2  galera::Monitor<galera::ReplicatorSMM::CommitOrder>::enter (this=this@entry=0x295ed58, obj=...) at galera/src/monitor.hpp:126
#3  0x00007fde87b7c9d2 in galera::ReplicatorSMM::apply_trx (this=this@entry=0x295e2c0, recv_ctx=recv_ctx@entry=0x7fde2c000990, trx=trx@entry=0x7fde2c3d85a0) at galera/src/replicator_smm.cpp:471

Thread 99 (Thread 0x7fde78565700 (LWP 17204)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fde87b82fd5 in wait (cond=..., this=<optimized out>) at galerautils/src/gu_lock.hpp:56
#2  galera::Monitor<galera::ReplicatorSMM::CommitOrder>::enter (this=this@entry=0x295ed58, obj=...) at galera/src/monitor.hpp:126
#3  0x00007fde87b7c9d2 in galera::ReplicatorSMM::apply_trx (this=this@entry=0x295e2c0, recv_ctx=recv_ctx@entry=0x7fde28000990, trx=trx@entry=0x7fde28192a00) at galera/src/replicator_smm.cpp:471

Thread 101 (Thread 0x7fde78420700 (LWP 17209)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x000000000092c1d1 in os_cond_wait (mutex=0x2b04200, cond=0x2b04238) at /home/ayurchen/codership/mysql/5.5-23/storage/innobase/os/os0sync.c:207
#2  os_event_wait_low (event=event@entry=0x2b04200, reset_sig_count=<optimized out>, reset_sig_count@entry=1358587156070748) at /home/ayurchen/codership/mysql/5.5-23/storage/innobase/os/os0sync.c:609
#3  0x00000000008665bf in srv_suspend_mysql_thread (thr=0x7fde70151c28) at /home/ayurchen/codership/mysql/5.5-23/storage/innobase/srv/srv0srv.c:1721
#4  0x000000000084cb18 in row_mysql_handle_errors (new_err=new_err@entry=0x7fde7841c440, trx=trx@entry=0x7fde5020e818, thr=thr@entry=0x7fde70151c28, savept=savept@entry=0x0) at /home/ayurchen/codership/mysql/5.5-23/storage/innobase/row/row0mysql.c:598
#5  0x000000000085abc2 in row_search_for_mysql (buf=<optimized out>, mode=<optimized out>, prebuilt=0x7fde70151538, match_mode=1, direction=<optimized out>) at /home/ayurchen/codership/mysql/5.5-23/storage/innobase/row/row0sel.c:4670
#6  0x0000000000830701 in ha_innobase::index_read (this=0x7fde7014c4a0, buf=0x7fde7021ff60 "\341\020'", key_ptr=0x7fde702202f0 "\020'", key_len=4, find_flag=<optimized out>) at /home/ayurchen/codership/mysql/5.5-23/storage/innobase/handler/ha_innodb.cc:6473
#7  0x0000000000837f7b in ha_innobase::rnd_pos (this=0x7fde7014c4a0, buf=0x7fde7021ff60 "\341\020'", pos=0x7fde702202f0 "\020'") at /home/ayurchen/codership/mysql/5.5-23/storage/innobase/handler/ha_innodb.cc:6949
#8  0x000000000073ed64 in Rows_log_event::find_row (this=this@entry=0x7fde5034fcf0, rli=rli@entry=0x7fde5000b060) at /home/ayurchen/codership/mysql/5.5-23/sql/log_event.cc:9671
#9  0x000000000073f70e in Delete_rows_log_event::do_exec_row (this=0x7fde5034fcf0, rli=0x7fde5000b060) at /home/ayurchen/codership/mysql/5.5-23/sql/log_event.cc:10019
#10 0x0000000000735a28 in Rows_log_event::do_apply_event (this=0x7fde5034fcf0, rli=0x7fde5000b060) at /home/ayurchen/codership/mysql/5.5-23/sql/log_event.cc:8043
#11 0x0000000000590f42 in apply_event (rli=<optimized out>, this=0x7fde5034fcf0) at /home/ayurchen/codership/mysql/5.5-23/sql/log_event.h:1139
#12 wsrep_apply_rbr (thd=thd@entry=0x7fde50000990, rbr_buf=rbr_buf@entry=0x7fde5003dad0 "\022e\372P\023", buf_len=561, buf_len@entry=554) at /home/ayurchen/codership/mysql/5.5-23/sql/sql_parse.cc:7881
#13 0x0000000000596ad7 in wsrep_apply_cb (ctx=0x7fde50000990, buf=0x7fde5003dad0, buf_len=554, global_seqno=<optimized out>) at /home/ayurchen/codership/mysql/5.5-23/sql/sql_parse.cc:7960
#14 0x00007fde87b78f7f in apply_wscoll (trx=..., apply_cb=0x596a50 <wsrep_apply_cb(void*, void const*, unsigned long, long)>, recv_ctx=0x7fde50000990) at galera/src/replicator_smm.cpp:37
#15 apply_trx_ws (recv_ctx=recv_ctx@entry=0x7fde50000990, apply_cb=0x596a50 <wsrep_apply_cb(void*, void const*, unsigned long, long)>, commit_cb=0x5a0290 <wsrep_commit_cb(void*, long, bool)>, trx=...) at galera/src/replicator_smm.cpp:79
#16 0x00007fde87b7c9b0 in galera::ReplicatorSMM::apply_trx (this=this@entry=0x295e2c0, recv_ctx=recv_ctx@entry=0x7fde50000990, trx=trx@entry=0x7fde501b5520) at galera/src/replicator_smm.cpp:466

Thread 105 (Thread 0x7fde80840700 (LWP 16488)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fde87b82fd5 in wait (cond=..., this=<optimized out>) at galerautils/src/gu_lock.hpp:56
#2  galera::Monitor<galera::ReplicatorSMM::CommitOrder>::enter (this=this@entry=0x295ed58, obj=...) at galera/src/monitor.hpp:126
#3  0x00007fde87b7c9d2 in galera::ReplicatorSMM::apply_trx (this=this@entry=0x295e2c0, recv_ctx=recv_ctx@entry=0x7fde74000990, trx=trx@entry=0x7fde74261500) at galera/src/replicator_smm.cpp:471

Thread 107 (Thread 0x7fde784e3700 (LWP 17206)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fde87b82fd5 in wait (cond=..., this=<optimized out>) at galerautils/src/gu_lock.hpp:56
#2  galera::Monitor<galera::ReplicatorSMM::CommitOrder>::enter (this=this@entry=0x295ed58, obj=...) at galera/src/monitor.hpp:126
#3  0x00007fde87b7c9d2 in galera::ReplicatorSMM::apply_trx (this=this@entry=0x295e2c0, recv_ctx=recv_ctx@entry=0x7fde38000990, trx=trx@entry=0x7fde3801b5d0) at galera/src/replicator_smm.cpp:471