"Duplicate option" error when adding the LDAP schema to OpenLDAP

With:
 * keystone current trunk
 * slapd 2.4.25-1.1ubuntu4.1

When I try to add the schema, I have this error:

 root@dino:/etc/ldap# slaptest
olcObjectClasses: value #1 olcObjectClasses: Duplicate option before ( keystoneEnabled ) MAY ( mail $ userPassword ) )
ObjectClassDescription = "(" whsp
  numericoid whsp ; ObjectClass identifier
  [ "NAME" qdescrs ]
  [ "DESC" qdstring ]
  [ "OBSOLETE" whsp ]
  [ "SUP" oids ] ; Superior ObjectClasses
  [ ( "ABSTRACT" / "STRUCTURAL" / "AUXILIARY" ) whsp ]
                                  ; default structural
  [ "MUST" oids ] ; AttributeTypes
  [ "MAY" oids ] ; AttributeTypes
  whsp ")"
config error processing cn={3}keystone,cn=schema,cn=config: olcObjectClasses: Duplicate option before ( keystoneEnabled ) MAY ( mail $ userPassword ) )
slaptest: bad configuration file!

Removing those lines (see the patch):

   MUST ( keystoneName )
   MUST ( keystoneEnabled )

Make slaptest pass and slapd can run. I don't have tested further yet, I'll add more detail if the rest works.