Further info: slapd.1.log has entries like this:
bdb_search: 15 does not match filter
bdb_search: 16 does not match filter
bdb_search: 17 does not match filter
bdb_search: 18 does not match filter
send_ldap_result: conn=293 op=1 p=3
send_ldap_result: err=0 matched="" text=""
send_ldap_response: msgid=2 tag=101 err=0
ber_flush2: 154 bytes to sd 15
conn=293 op=1 SEARCH RESULT tag=101 err=0 nentries=0 text=
connection_get(15)
connection_get(15): got connid=293
connection_read(15): checking for input on id=293
ber_get_next
ber_get_next: tag 0x30 len 5 contents:
ber_get_next
ber_get_next on fd 15 failed errno=0 (Undefined error: 0)
connection_closing: readying conn=293 sd=15 for close
connection_close: deferring conn=293 sd=15
conn=293 op=2 do_unbind
conn=293 op=2 UNBIND
connection_resched: attempting closing conn=293 sd=15
connection_close: conn=293 sd=15
conn=293 fd=15 closed
Note the error...