memcached crashes during bucket deletion after rebalancing out all the nodes

http://qa.hq.northscale.net/view/1.8.1/job/centos-64-getr-tests/lastSuccessfulBuild/artifact/core-10.1.2.31-0.log

Program terminated with signal 11, Segmentation fault.
#0 0x00007f02ca784810 in ?? ()
(gdb) bt
#0 0x00007f02ca784810 in ?? ()
#1 0x00007f02cf188061 in MallocHook::InvokeDeleteHookSlow (p=0x776900) at src/malloc_hook.cc:529
#2 0x00007f02cf18d695 in MallocHook::InvokeDeleteHook (ptr=0x776900) at src/malloc_hook-inl.h:176
#3 tc_free (ptr=0x776900) at src/tcmalloc.cc:1498
#4 0x00007f02cfeaabc8 in ?? () from /lib64/ld-linux-x86-64.so.2
#5 0x00007f02cfeab29c in ?? () from /lib64/ld-linux-x86-64.so.2
#6 0x00007f02cfea4986 in ?? () from /lib64/ld-linux-x86-64.so.2
#7 0x00007f02cf8492ac in ?? () from /lib/libdl.so.2
#8 0x00007f02cf84900f in dlclose () from /lib/libdl.so.2
#9 0x00007f02cd298dbb in uninit_engine_handle (arg=0x83e000) at bucket_engine.c:722
#10 free_engine_handle (arg=0x83e000) at bucket_engine.c:731
#11 engine_shutdown_thread (arg=0x83e000) at bucket_engine.c:1460
#12 0x00007f02cef589ca in start_thread () from /lib/libpthread.so.0
#13 0x00007f02cecb570d in clone () from /lib/libc.so.6
#14 0x0000000000000000 in ?? ()
(gdb) t a a bt

Thread 3 (Thread 7526):
#0 0x00007f02cec7939d in nanosleep () from /lib/libc.so.6
#1 0x00007f02cec79210 in sleep () from /lib/libc.so.6
#2 0x00000000004167a8 in check_isasl_db_thread (arg=<value optimized out>) at daemon/isasl.c:233
#3 0x00007f02cef589ca in start_thread () from /lib/libpthread.so.0
#4 0x00007f02cecb570d in clone () from /lib/libc.so.6
#5 0x0000000000000000 in ?? ()

Thread 2 (Thread 7516):
#0 0x00007f02cef5d85c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1 0x00007f02cd298f93 in bucket_destroy (handle=<value optimized out>, force=<value optimized out>) at bucket_engine.c:1330
#2 0x00000000004090a0 in main (argc=<value optimized out>, argv=<value optimized out>) at daemon/memcached.c:7484

Thread 1 (Thread 7537):
#0 0x00007f02ca784810 in ?? ()
#1 0x00007f02cf188061 in MallocHook::InvokeDeleteHookSlow (p=0x776900) at src/malloc_hook.cc:529
#2 0x00007f02cf18d695 in MallocHook::InvokeDeleteHook (ptr=0x776900) at src/malloc_hook-inl.h:176
#3 tc_free (ptr=0x776900) at src/tcmalloc.cc:1498
#4 0x00007f02cfeaabc8 in ?? () from /lib64/ld-linux-x86-64.so.2
#5 0x00007f02cfeab29c in ?? () from /lib64/ld-linux-x86-64.so.2
#6 0x00007f02cfea4986 in ?? () from /lib64/ld-linux-x86-64.so.2
#7 0x00007f02cf8492ac in ?? () from /lib/libdl.so.2
#8 0x00007f02cf84900f in dlclose () from /lib/libdl.so.2
#9 0x00007f02cd298dbb in uninit_engine_handle (arg=0x83e000) at bucket_engine.c:722
#10 free_engine_handle (arg=0x83e000) at bucket_engine.c:731
#11 engine_shutdown_thread (arg=0x83e000) at bucket_engine.c:1460
#12 0x00007f02cef589ca in start_thread () from /lib/libpthread.so.0
#13 0x00007f02cecb570d in clone () from /lib/libc.so.6
#14 0x0000000000000000 in ?? ()