Comment 4 for bug 921489

I instaled slapd-dbg and i have more informations:
#0 syncrepl_entry (si=0x7fbe0206c4c0, op=0x7fbdfb537470, entry=0x7fbe020dab78, modlist=<value optimized out>,
    syncstate=<value optimized out>, syncUUID=<value optimized out>, syncCSN=0x0)
    at /build/buildd/openldap-2.4.21/servers/slapd/syncrepl.c:2428
#1 0x00007fbe01c29fd4 in do_syncrep2 (op=0x7fbdfb537470, si=0x7fbe0206c4c0) at /build/buildd/openldap-2.4.21/servers/slapd/syncrepl.c:939
#2 0x00007fbe01c2ccd7 in do_syncrepl (ctx=<value optimized out>, arg=0x7fbe0206b470)
    at /build/buildd/openldap-2.4.21/servers/slapd/syncrepl.c:1432
#3 0x00007fbe017262d8 in ldap_int_thread_pool_wrapper (xpool=<value optimized out>)
    at /build/buildd/openldap-2.4.21/libraries/libldap_r/tpool.c:685
#4 0x00007fbdffbc79ca in start_thread () from /lib/libpthread.so.0
#5 0x00007fbdff92416d in clone () from /lib/libc.so.6
#6 0x0000000000000000 in ?? ()