Why won't slapd shutdown (kill -0)?

This has been happening for a long time with current and hasn't been
resolved.  When I start up slapd, I cannot stop it without kill -9 ing
it.  It would appear stuck in kse and probably has something to do with
kill -0:

(gdb) bt
#0  0x000000080142e914 in kse_release () at kse_release.S:2
#1  0x0000000801428e49 in kse_wait (kse=0x62a000, td_wait=0x0,
sigseqno=0)
    at /usr/src/lib/libpthread/thread/thr_kern.c:1843
#2  0x0000000801427078 in kse_sched_multi (kmbx=0x62efa0)
    at /usr/src/lib/libpthread/thread/thr_kern.c:1039
#3  0x000000080142afbf in _amd64_enter_uts ()
    at /usr/src/lib/libpthread/arch/amd64/amd64/enter_uts.S:40
#4  0x0000000000000000 in ?? ()
#5  0x000000000062f000 in ?? ()
#6  0x000000000062a000 in ?? ()
#7  0x0000000000000000 in ?? ()
#8  0x0000000000000000 in ?? ()
#9  0x0000000000000000 in ?? ()
#10 0x0000000000000000 in ?? ()
#11 0x0000000000000000 in ?? ()
#12 0x0000000000000001 in ?? ()
#13 0x0000000801426dd0 in _thr_sched_switch_unlocked ()
    at /usr/src/lib/libpthread/thread/thr_kern.c:904
Previous frame inner to this frame (corrupt stack?)