excluded view doesn't work

my version is 5.1.1

my snmpd.conf is:
com2sec sec1 default public
group gp1 v1 sec1
view vn1 excluded system
access gp1 "" any noauth exact vn1 none none

according to the config I can visit every nodes except
system and it's subtree.

but in vacm_vars.c
vacm_in_view() {
...
vp = vacm_getViewEntry(vn, name, namelen,
VACM_MODE_FIND);

if \(vp == NULL\) \{
    return 4;
\}

if \(vp->viewType == SNMP\_VIEW\_EXCLUDED\) \{
    return 5;
\}

...
}

if I visit sysName.0, vp will not be NULL, vp->viewType
== SNMP_VIEW_EXCLUDED, it returns 5.
if I visit ifType.1, vp will be NULL, it returns 4
so if I use "excluded view" it will always return errors.