(ITS#8621) Unique through multiple attribute

[tatarenko@alpha-it.ru]

Full_Name: Tatarenko Vasily
Version: 2.4.44
OS: Freebsd 11.0
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (128.74.103.57)


When use Unique overlay it is not possible to prevent users from inserting value
in attributeA (like otherMailbox) that is already was used in attributeB (like
mail) through whole domain.
If i put multiple attributes to Unique overlay it still search through one
attribute. 
If i use 
olcUniqueURI: ldap:///dc=instatsport,dc=com?mail,otherMailbox,proxyAddresses?sub
Unique overlay still make this search for mail:
   unique_search (|(mail=123@example.com))
And this search for otherMailbox
   unique_search (|(otherMailbox=123@example.com))