Description of problem:
Group enumeration fails in proxy provider

Version-Release number of selected component (if applicable):
1.8.0-25

How reproducible:
Always

Steps to Reproduce:
1. Configure nss_ldap and verify if enumeration works via nss_ldap:

# getent -s ldap group
Group1:*:1001:puser1
Group2:*:1002:
Group3:*:999:
Group4:*:1011:
Duplicate:*:1010:

# getent -s ldap passwd
puser1:*:1001:1001:Posix User1:/home/puser1:/bin/bash
puser2:*:1002:1002:Posix User2:/home/puser2:/bin/bash
puser3:*:999:999:Posix User1:/home/puser3:/bin/bash
puser4:*:1011:1011:Posix User4:/home/puser4:


2. Configure sssd via proxy:

[domain/PROXY]
id_provider = proxy
auth_provider = proxy
debug_level = 0xFFF0
proxy_lib_name = ldap
proxy_pam_target = sssdproxyldap
enumerate = true


3. Check if enumeration works via sssd:

# getent -s sss passwd
puser1:*:1001:1001:Posix User1:/home/puser1:/bin/bash
puser2:*:1002:1002:Posix User2:/home/puser2:/bin/bash
puser3:*:999:999:Posix User1:/home/puser3:/bin/bash
puser4:*:1011:1011:Posix User4:/home/puser4:

# getent -s sss group
                      <== Nothing is returned


Actual results:
Group enumeration fails.

Expected results:
Group enumeration should succeed.

Additional info: