Is pillar_ldap external module is broken in 3001 ?

Description of Issue

Hello, I've just upgraded a syndic from version 2018.3.4 to 3001 and it seems that external ldap pillar module /usr/lib/python3/dist-packages/salt/pillar/pillar_ldap.py is not working anymore. The only LDAP module which exists for python3 is python3-ldap3 which is not loadable through "import ldap" code bellow :

134 # Import salt libs
135 import salt.utils.data
136 from salt.exceptions import SaltInvocationError
137
138 try:
**139     import ldap  # pylint: disable=W0611**
140
141     HAS_LDAP = True
142 except ImportError:
143     HAS_LDAP = False

Setup

Install salt master version 3001, python3-ldap3 package and configure it like this :

[root@hostname pillar]# cat /etc/salt/master.d/pillars.conf
ext_pillar:
  - pillar_ldap: /etc/salt/master.d/pillar_ldap.yaml

[root@hostname pillar]# cat /etc/salt/master.d/pillar_ldap.yaml
salt-groups:
  server: ldaphost.domain.tld
  port: 389
  tls: false
  dn: 'ou=group,dc=unix,,dc=fr'
  referrals: false
  anonymous: true
  mode: map
  filter: 'objectclass=posixgroup'
  attrs:
    - cn
    - gidNumber

search_order:
  - salt-groups

Restart salt master, logs like thoose appears :
2020-10-19 15:51:01,266 [salt.utils.lazy :106 ][DEBUG ][27269] Could not LazyLoad pillar_ldap.ext_pillar: 'pillar_ldap' __virtual__ returned False

due to this :

#  python3
Python 3.5.2 (default, Jul 17 2020, 14:04:10)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import ldap
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named 'ldap'
>>> import ldap3
>>>

Steps to Reproduce Issue

$ salt-call pillar.get salt-groups
$

Versions Report

# salt --versions-report
Salt Version:
           Salt: 3001

Dependency Versions:
           cffi: 1.5.2
       cherrypy: 3.5.0
       dateutil: 2.4.2
      docker-py: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
         Jinja2: 2.8
        libgit2: 0.24.0
       M2Crypto: Not Installed
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.6.2
   mysql-python: Not Installed
      pycparser: 2.14
       pycrypto: Not Installed
   pycryptodome: 3.4.7
         pygit2: 0.24.0
         Python: 3.5.2 (default, Jul 17 2020, 14:04:10)
   python-gnupg: 0.3.8
         PyYAML: 3.11
          PyZMQ: 17.1.2
          smmap: Not Installed
        timelib: Not Installed
        Tornado: 4.5.3
            ZMQ: 4.1.4

System Versions:
           dist: ubuntu 16.04 Xenial Xerus
         locale: UTF-8
        machine: x86_64
        release: 4.4.0-190-generic
         system: Linux
        version: Ubuntu 16.04 Xenial Xerus

Start with /usr/lib/python3/dist-packages/salt/pillar/pillar_ldap.py, especially its import and virtual handling, then reproduce the failure with the supplied pillar_ldap.yaml and salt-call pillar.get salt-groups. Done means the external pillar loads with the reported Python 3 LDAP dependency and returns the configured group data instead of reporting that virtual returned False.