memcached stucks in shutdown code

Was running cluster_run cluster and stopped it by Ctrl-C (which is not delivered to memcached). All memcached's died normally. One seems to hang. Here's backtrace:

(gdb) thread app all bt

Thread 2 (Thread 0xf298ab70 (LWP 4846)):
#0 0xf772f430 in __kernel_vsyscall ()
#1 0xf767af02 in __lll_lock_wait () at ../nptl/sysdeps/unix/sysv/linux/i386/i686/../i486/lowlevellock.S:142
#2 0xf767639b in _L_lock_728 () from /lib/i386-linux-gnu/i686/cmov/libpthread.so.0
#3 0xf76761c1 in __pthread_mutex_lock (mutex=mutex@entry=0xc90bb64) at pthread_mutex_lock.c:61
#4 0x0804d9a4 in release_cookie (cookie=0xc8da8d8) at daemon/memcached.c:6691
#5 0xf771fc12 in bucket_engine_release_cookie (cookie=0xc8da8d8) at bucket_engine.c:2519
#6 0xf4343fa4 in EventuallyPersistentEngine::releaseCookie (this=0xc93a4c8, cookie=0xc8da8d8) at ep_engine.cc:1192
#7 0xf437d04b in TapConnection::releaseReference (this=0xf1800a10, force=false) at tapconnection.cc:65
#8 0xf438f72b in TapConnectionReaperCallback::callback (this=0xc90bd38) at tapconnmap.cc:29
#9 0xf4326855 in Task::run (this=0xca3dc40, d=..., t=...) at dispatcher.hh:139
#10 0xf4324713 in Dispatcher::run (this=0xc95ea08) at dispatcher.cc:123
#11 0xf43261ea in launch_dispatcher_thread (arg=0xc95ea08) at dispatcher.cc:28
#12 0xf7673c39 in start_thread (arg=0xf298ab70) at pthread_create.c:304
#13 0xf75e127e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 1 (Thread 0xf750f6c0 (LWP 4793)):
#0 0xf772f430 in __kernel_vsyscall ()
#1 0xf7674e65 in pthread_join (threadid=4070091632, thread_return=0x0) at pthread_join.c:89
#2 0xf43203d0 in Dispatcher::stop (this=0xc95ea08, force=false) at dispatcher.cc:162
#3 0xf432c8f7 in EventuallyPersistentStore::~EventuallyPersistentStore (this=0xc94b9b0, __in_chrg=<optimized out>) at ep.cc:676
#4 0xf43595b4 in EventuallyPersistentEngine::~EventuallyPersistentEngine (this=0xc93a4c8, __in_chrg=<optimized out>) at ep_engine.h:511
#5 0xf4347fc5 in EvpDestroy (handle=0xc93a4c8, force=false) at ep_engine.cc:125
#6 0xf771c5fa in bucket_shutdown_engine (key=0xc93a4b8, nkey=7, val=0xc90c150, nval=0, args=0x0) at bucket_engine.c:1289
#7 0xf7721c59 in genhash_iter (h=0xc8f5330, iterfunc=iterfunc@entry=0xf771c5a0 <bucket_shutdown_engine>, arg=arg@entry=0x0) at genhash.c:275
#8 0xf7720ae2 in bucket_destroy (handle=0xf77253e0, force=<optimized out>) at bucket_engine.c:1326
#9 bucket_destroy (handle=0xf77253e0, force=false) at bucket_engine.c:1306
#10 0x0804be30 in main (argc=19, argv=0xffeb7ab4) at daemon/memcached.c:7921

Both threads seem to be stuck and unable to proceed