crash in CheckpointManager::checkOpenCheckpoint_UNLOCKED during rebalancing

#0 0x00007fde93d504a3 in epoll_wait () from /lib64/libc.so.6
#1 0x00007fde948afc28 in epoll_dispatch (base=0x23c0b10, tv=<value optimized out>) at epoll.c:404
#2 0x00007fde9489ea4c in event_base_loop (base=0x23c0b10, flags=0) at event.c:1558
#3 0x0000000000409974 in main (argc=<value optimized out>, argv=<value optimized out>) at daemon/memcached.c:7459

Thread 6 (Thread 19341):
#0 0x00007fde93d1546d in nanosleep () from /lib64/libc.so.6
#1 0x00007fde93d152e0 in sleep () from /lib64/libc.so.6
#2 0x0000000000414f58 in check_isasl_db_thread (arg=<value optimized out>) at daemon/isasl.c:233
#3 0x00007fde93fe87e1 in start_thread () from /lib64/libpthread.so.0
#4 0x00007fde93d4fead in clone () from /lib64/libc.so.6

Thread 5 (Thread 19340):
#0 0x00007fde93d42b5d in read () from /lib64/libc.so.6
#1 0x00007fde93ce0228 in _IO_new_file_underflow () from /lib64/libc.so.6
#2 0x00007fde93ce1d2e in _IO_default_uflow_internal () from /lib64/libc.so.6
#3 0x00007fde93cdd24b in getc () from /lib64/libc.so.6
#4 0x00007fde93a6e855 in check_stdin_thread (arg=0x4034b0) at extensions/daemon/stdin_check.c:19
#5 0x00007fde93fe87e1 in start_thread () from /lib64/libpthread.so.0
#6 0x00007fde93d4fead in clone () from /lib64/libc.so.6

Thread 4 (Thread 19356):
#0 0x00007fde93fec7a9 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00007fde7bc906b0 in Dispatcher::start (this=0x7fde8e017804) at dispatcher.cc:39
#2 0x000000004de880f5 in ?? ()
#3 0x000000000785ef10 in ?? ()
#4 0x00007fde7a728df0 in ?? ()
#5 0x00007fde7bc8ce27 in ~pair (this=0x7fde7a729700, k=<value optimized out>)
at /usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/stl_pair.h:69
#6 Internal::map_base<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, index_entry>, Internal::extract1st<std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, index_entry> >, true, std::tr1::hashtable<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, index_entry>, std::allocator<std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, index_entry> >, Internal::extract1st<std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, index_entry> >, std::equal_to<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::tr1::hash<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Internal::mod_range_hashing, Internal::default_ranged_hash, Internal::prime_rehash_policy, false, false, true> >::operator[] (this=0x7fde7a729700, k=<value optimized out>)
at /usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/tr1/hashtable:691
#7 0x0000000000000000 in ?? ()

Thread 3 (Thread 19354):
#0 0x00007fde93fec43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00007fde7bc92823 in Dispatcher::completeNonDaemonTasks (this=0x7fde7b72b700) at dispatcher.cc:234
#2 0x0000000000000000 in ?? ()

Thread 2 (Thread 19355):
#0 0x00007fde93fec7a9 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00007fde7bc906b0 in Dispatcher::start (this=0x7fde8d0d5324) at dispatcher.cc:39
#2 0x000000004de880f2 in ?? ()
#3 0x000000000d8c0480 in ?? ()
#4 0x00007fde7af29df0 in ?? ()
#5 0x00007fde7bc8ce27 in ~pair (this=0x7fde7af2a700, k=<value optimized out>)
at /usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/stl_pair.h:69
#6 Internal::map_base<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, index_entry>, Internal::extract1st<std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, index_entry> >, true, std::tr1::hashtable<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, index_entry>, std::allocator<std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, index_entry> >, Internal::extract1st<std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, index_entry> >, std::equal_to<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::tr1::hash<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Internal::mod_range_hashing, Internal::default_ranged_hash, Internal::prime_rehash_policy, false, false, true> >::operator[] (this=0x7fde7af2a700, k=<value optimized out>)
at /usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/tr1/hashtable:691
#7 0x0000000000000000 in ?? ()

Thread 1 (Thread 19343):
#0 0x00007fde93ca16b5 in raise () from /lib64/libc.so.6
#1 0x00007fde93ca2e95 in abort () from /lib64/libc.so.6
#2 0x00007fde93c9a645 in __assert_fail () from /lib64/libc.so.6
#3 0x00007fde7bc89b06 in get (this=0x7fde92860da0, forceCreation=false, timeBound=48) at atomic.hh:109
#4 operator unsigned int (this=0x7fde92860da0, forceCreation=false, timeBound=48) at atomic.hh:118
#5 CheckpointManager::checkOpenCheckpoint_UNLOCKED (this=0x7fde92860da0, forceCreation=false, timeBound=48) at checkpoint.cc:710
#6 0x00007fde8ed2fff0 in ?? ()
#7 0x00000000000003f9 in ?? ()
#8 0x00007fde8ed2ffe0 in ?? ()
#9 0x00007fde8ed2ff20 in ?? ()
#10 0x00007fde8c307500 in ?? ()
#11 0x0000000000000000 in ?? ()