[SSSD] [sssd PR#103][comment] sudo: do not store usn if no rules are found

[fidencio]

URL: https://github.com/SSSD/sssd/pull/103
Title: #103: sudo: do not store usn if no rules are found

lslebodn commented:
"""
There is a simple domain config with case_preserving
```
        [domain/LDAP]
        id_provider = ldap
        ldap_uri = ldap://$SERVER
        ldap_search_base = $DS_BASE_DN
        ldap_tls_cacert = /etc/openldap/certs/cacert.asc
        case_sensitive = preserving
```
Then you will add a service entry to LDAP server
```
    dn: cn=Svc1,ou=Services,$DS_BASE_DN
    objectClass: ipService
    cn: Svc1_Alias
    ipServicePort: 1234
    ipServiceProtocol: Tcp
```
and then try to run few getent commands for service
* getent services SVC1 | grep Svc1 # passed
* getent services svc1_alias | grep Svc1 # passed
* getent services 1234/TCP # failed
"""

See the full comment at https://github.com/SSSD/sssd/pull/103#issuecomment-264888745