segfault during failover tests in BlockTimer

#0 0x00002aaaaad48e37 in BlockTimer::~BlockTimer() () from /opt/couchbase/lib/memcached/ep.so
(gdb) thread apply all bt

Thread 13 (Thread 0x2adabd694240 (LWP 20104)):
#0 0x00002adabcf008a8 in epoll_wait () from /lib64/libc.so.6
#1 0x00002adabc10dba6 in epoll_dispatch (base=0x1b818000, tv=<value optimized out>) at epoll.c:404
#2 0x00002adabc0fcc11 in event_base_loop (base=0x1b818000, flags=0) at event.c:1558
#3 0x00000000004095b2 in main (argc=<value optimized out>, argv=<value optimized out>) at daemon/memcached.c:7900

Thread 12 (Thread 20112):
#0 0x00002adabcef278b in read () from /lib64/libc.so.6
#1 0x00002adabce98d57 in _IO_new_file_underflow () from /lib64/libc.so.6
#2 0x00002adabce9971e in _IO_default_uflow_internal () from /lib64/libc.so.6
#3 0x00002adabce94fdb in getc () from /lib64/libc.so.6
#4 0x00002adabd695879 in check_stdin_thread (arg=0x4033f0) at extensions/daemon/stdin_check.c:19
#5 0x00002adabcc1773d in start_thread () from /lib64/libpthread.so.0
#6 0x00002adabcf004bd in clone () from /lib64/libc.so.6

Thread 11 (Thread 20114):
#0 0x00002adabcec6541 in nanosleep () from /lib64/libc.so.6
#1 0x00002adabcec6364 in sleep () from /lib64/libc.so.6
#2 0x0000000000415c58 in check_isasl_db_thread (arg=<value optimized out>) at daemon/isasl.c:233
#3 0x00002adabcc1773d in start_thread () from /lib64/libpthread.so.0
#4 0x00002adabcf004bd in clone () from /lib64/libc.so.6

Thread 10 (Thread 20115):
#0 0x00002adabcf008a8 in epoll_wait () from /lib64/libc.so.6
#1 0x00002adabc10dba6 in epoll_dispatch (base=0x1b818500, tv=<value optimized out>) at epoll.c:404
#2 0x00002adabc0fcc11 in event_base_loop (base=0x1b818500, flags=0) at event.c:1558
#3 0x0000000000414074 in worker_libevent (arg=0x173b8500) at daemon/thread.c:305
#4 0x00002adabcc1773d in start_thread () from /lib64/libpthread.so.0
#5 0x00002adabcf004bd in clone () from /lib64/libc.so.6

Thread 9 (Thread 20116):
#0 0x00002adabcf008a8 in epoll_wait () from /lib64/libc.so.6
#1 0x00002adabc10dba6 in epoll_dispatch (base=0x1b818280, tv=<value optimized out>) at epoll.c:404
#2 0x00002adabc0fcc11 in event_base_loop (base=0x1b818280, flags=0) at event.c:1558
#3 0x0000000000414074 in worker_libevent (arg=0x173b8600) at daemon/thread.c:305
#4 0x00002adabcc1773d in start_thread () from /lib64/libpthread.so.0
#5 0x00002adabcf004bd in clone () from /lib64/libc.so.6

Thread 8 (Thread 20117):
#0 0x00002adabcf008a8 in epoll_wait () from /lib64/libc.so.6
#1 0x00002adabc10dba6 in epoll_dispatch (base=0x1b818c80, tv=<value optimized out>) at epoll.c:404
#2 0x00002adabc0fcc11 in event_base_loop (base=0x1b818c80, flags=0) at event.c:1558
#3 0x0000000000414074 in worker_libevent (arg=0x173b8700) at daemon/thread.c:305
#4 0x00002adabcc1773d in start_thread () from /lib64/libpthread.so.0
#5 0x00002adabcf004bd in clone () from /lib64/libc.so.6

Thread 7 (Thread 20118):
#0 0x00002adabcf008a8 in epoll_wait () from /lib64/libc.so.6
#1 0x00002adabc10dba6 in epoll_dispatch (base=0x1b818a00, tv=<value optimized out>) at epoll.c:404
#2 0x00002adabc0fcc11 in event_base_loop (base=0x1b818a00, flags=0) at event.c:1558
#3 0x0000000000414074 in worker_libevent (arg=0x173b8800) at daemon/thread.c:305
#4 0x00002adabcc1773d in start_thread () from /lib64/libpthread.so.0
#5 0x00002adabcf004bd in clone () from /lib64/libc.so.6

Thread 6 (Thread 20119):
#0 0x00002adabcf008a8 in epoll_wait () from /lib64/libc.so.6
#1 0x00002adabc10dba6 in epoll_dispatch (base=0x1b818780, tv=<value optimized out>) at epoll.c:404
#2 0x00002adabc0fcc11 in event_base_loop (base=0x1b818780, flags=0) at event.c:1558
#3 0x0000000000414074 in worker_libevent (arg=0x173b8900) at daemon/thread.c:305
#4 0x00002adabcc1773d in start_thread () from /lib64/libpthread.so.0
#5 0x00002adabcf004bd in clone () from /lib64/libc.so.6

Thread 5 (Thread 20120):
#0 0x00002adabcec6541 in nanosleep () from /lib64/libc.so.6
#1 0x00002adabcef9ed4 in usleep () from /lib64/libc.so.6
#2 0x00002aaaaad6c842 in MemoryTracker::MemoryTracker (this=0x173b67c0) at memory_tracker.cc:79
#3 0x0000000000000000 in ?? ()

Thread 4 (Thread 20121):
#0 0x00002adabcc1bee9 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00002aaaaad2d7c7 in JobLogEntry (this=0x1b87ea80) at dispatcher.hh:40
#2 Dispatcher::run (this=0x1b87ea80) at dispatcher.cc:141
#3 0x00002aaaaad2ddfb in _M_dispose (this=0xffffffffffffffe8) at /usr/lib/gcc/x86_64-redhat-linux6E/4.4.6/../../../../include/c++/4.4.6/bits/basic_string.h:236
#4 ~basic_string (this=0xffffffffffffffe8) at /usr/lib/gcc/x86_64-redhat-linux6E/4.4.6/../../../../include/c++/4.4.6/bits/basic_string.h:503
#5 Dispatcher::run (this=0xffffffffffffffe8) at dispatcher.cc:110
#6 0x0000000000000000 in ?? ()

Thread 3 (Thread 20123):
#0 0x00002adabcc1c150 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00002aaaaad2af80 in Dispatcher::wake (this=0x47d8f0b0, task=<value optimized out>, outtid=<value optimized out>) at dispatcher.cc:209
#2 0x0000000047d8f0ba in ?? ()
#3 0x0000000047d8f0bb in ?? ()
#4 0x0000000000000000 in ?? ()

Thread 2 (Thread 20124):
#0 0x00002adabcc1c150 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00002aaaaad4b29f in wait (this=0x1b8a2044) at syncobject.hh:61
#2 wait (this=0x1b8a2044) at tapconnmap.hh:171
#3 EventuallyPersistentEngine::notifyPendingConnections (this=0x1b8a2044) at ep_engine.cc:3380
#4 0x00002aaaaad4b383 in advance_tv (this=0x1b88a000) at common.hh:82
#5 wait (this=0x1b88a000) at syncobject.hh:62
#6 wait (this=0x1b88a000) at tapconnmap.hh:171
#7 EventuallyPersistentEngine::notifyPendingConnections (this=0x1b88a000) at ep_engine.cc:3380
#8 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x4738e940 (LWP 20122)):
#0 0x00002aaaaad48e37 in BlockTimer::~BlockTimer() () from /opt/couchbase/lib/memcached/ep.so
#1 0x00002adabc9dea07 in MallocExtension::instance () at src/malloc_extension.cc:207
#2 0x0001000000000000 in ?? ()
#3 0x00002aaaab0c2a90 in typeinfo for FlusherStepper () from /opt/couchbase/lib/memcached/ep.so
#4 0x0000000000000000 in ?? ()