ldap_search not working with base=NULL after php7.1

Description

The following code:

<?php
$ds = ldap_connect(); // <-- URI from /etc/openldap/ldap.conf
ldap_set_option($ds, LDAP_OPT_PROTOCOL_VERSION, 3);

$sr = ldap_search($ds, NULL, "(uid=dab)", array("dn"));  // <-- BASE from /etc/openldap/ldap.conf
$entry = ldap_first_entry($ds, $sr);
var_dump($entry);

Resulted in this output:

Warning: ldap_search(): Search: No such object in test.php on line 5

But I expected this output instead:

resource(6) of type (ldap result entry)

/etc/openldap/ldap.conf:
BASE c=ru
URI ldap://localhost

slapd.log:
version <=php7.1
slapd[14091]: conn=4230904 op=0 SRCH base="c=ru" scope=2 deref=0 filter="(uid=dab)"
version >php7.1
slapd[14091]: conn=4230791 op=0 SRCH base="" scope=2 deref=0 filter="(uid=dab)"

related bug&commit:
https://bugs.php.net/bug.php?id=77958
https://github.com/php/php-src/commit/5d2fe48785b6d24102ff53e78631cba7f2aefbef

PHP Version

PHP 8.0.12

Operating System

gentoo

从 ldap_search 入口点开始，将复现中显示的行为与链接的 bug 以及提交 5d2fe48785b6d24102ff53e78631cba7f2aefbef 进行比较。使用所述 LDAP 配置运行提供的 PHP 脚本并检查 slapd.log；当 NULL base 使用已配置的 BASE 且搜索返回预期条目时，即表示完成。