As it is written there, "Replacing attribute values is always done with a ldap.MOD_DELETE/ldap.MOD_ADD pair instead of ldap.MOD_REPLACE to work-around potential issues with attributes for which no EQUALITY matching rule are defined in the server's subschema. This works correctly in most situations but rarely fails with some LDAP servers implementing (schema) checks on transient state entry during processing the modify operation."
And this strategy would work just fine, because it deletes all values before doing the add. It's essentially what the REPLACE op does anyway.
--Quanah -- Quanah Gibson-Mount Product Architect Symas Corporation Packaged, certified, and supported LDAP solutions powered by OpenLDAP: <http://www.symas.com>