ldapd dies with assert failure

I've tried to pare this down. Never used ldapd before but hoping it can
replace slapd for my needs. I'm not sure if this is a bug, or if I'm
missing something in the process of setting up a new directory.

Starting with a new patched/stable system:


$ uname -mrsv
OpenBSD 6.1 GENERIC.MP#6 amd64


$ doas cat /etc/ldapd.conf
listen on "/var/run/ldapd.sock"

rootdn "cn=admin,dc=example,dc=org"
rootpw "test1234"

schema "/etc/ldap/core.schema"

namespace "dc=example,dc=org" {
index objectClass
}


$ cat init.ldif
dn: dc=example,dc=org
objectClass: dcObject
objectClass: organization
o: Example Org
dc: example



First startup, no existing db files....

$ doas ldapd -d
May 24 13:54:54.474 [25253] startup
May 24 13:54:54.718 [68140] listening on /var/run/ldapd.sock
May 24 13:54:54.725 [68140] opening namespace dc=example,dc=org


At this point in another terminal I run:

$ cat init.ldif | ldapadd -H ldapi://%2Fvar%2Frun%2Fldapd.sock -D "cn=admin,dc=example,dc=org" -W
Enter LDAP Password:
adding new entry "dc=example,dc=org"
ldap_result: Can't contact LDAP server (-1)



And back on the first terminal I see:

assertion "p->upper >= p->lower" failed: file "/usr/src/usr.sbin/ldapd/btree.c", line 1949, function "btree_add_node"
May 24 13:55:17.142 [25253] ldapd: removing unix socket /var/run/ldapd.sock



As above, with -v arg to ldapd, the messages are:

May 24 14:08:09.938 [42637] accepted local connection by uid 1001
May 24 14:08:09.947 [42637] consumed 48 bytes
May 24 14:08:09.948 [42637] got request type 0, id 1
May 24 14:08:09.948 [42637] bind dn = cn=admin,dc=example,dc=org
May 24 14:08:09.948 [42637] successfully authenticated as cn=admin,dc=example,dc=org
May 24 14:08:09.948 [42637] sending response 1 with result 0
May 24 14:08:09.957 [42637] consumed 106 bytes
May 24 14:08:09.957 [42637] got request type 8, id 2
May 24 14:08:09.957 [42637] adding entry dc=example,dc=org
assertion "p->upper >= p->lower" failed: file "/usr/src/usr.sbin/ldapd/btree.c", line 1949, function "btree_add_node"
May 24 14:08:09.997 [28992] ldapd: removing unix socket /var/run/ldapd.sock
May 24 14:08:10.008 [28992] ldapd: exiting