Retrieve the user objectclasses when checking for existence
This saves at least one search per user-mod because the current
set of objectclasses are verified to ensure they are complete
on each update.
So always retrieve them in get_either_dn(). They are used by
every call but there is negligible overhead in retrieving
this from LDAP.
https://pagure.io/freeipa/issue/8801
Signed-off-by: Rob Crittenden <rcritten@redhat.com>
Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>