I am sending, from Python, the following modify_s(dn, modlist) command:

dn
'CN=brian,CN=Users,DC=ad,DC=vpac,DC=org'

modlist
[(1, 'objectClass', None),
 (0,
  'objectClass',
  ['organizationalPerson',
   'top',
   'inetOrgPerson',
   'person',
   'user',
   'posixAccount']),
 (0, 'title', ['Destroyer']),
 (0, 'mail', ['None@vpac.org']),
 (0, 'givenName', ['Brian']),
 (0, 'gecos', ['Brian May']),
 (0, 'sn', ['May']),
 (0, 'homeDirectory', ['/home/None'])]


This gives me:

{'info': "0000200D: objectclass: cannot re-add an existing
objectclass: 'organizationalPerson'!", 'desc': 'Type or value exists'}

I believe the first item in the modlist should delete
the objectClass, so it shouldn't exist when it tries to add it again.
Or maybe the first delete isn't suppose to work for some reason?