LDAP backend adds more than one objectClass constraint in search filter for some requests

[Ivan Mironov]

Here is an example from one of unit tests:

    LDAP search: base=ou=UserGroups,cn=example,cn=com scope=1 filterstr=(&(&(objectClass=groupOfNames)(member=cn=c76bdcc076294c95a7dd3bb2a200fc05,ou=Users,cn=example,cn=com))(objectClass=groupOfNames)) attrs=['ou', 'cn', 'description'] attrsonly=0

This is not an error, just minor shortcoming.