[Samba] Disable Pam checking for Samba4 Standalone role server with samdb_dbds as passdb backend !

[CpServiceSPb .]

There is Samba4 4.1.8 as StandAlone server role is installed at ubuntu
14.04 LTS from sources.
There is samdb_dbds as passdb backend.
Provisioning and adding user to Samba4 is successful.
But there is no such user exactly at Ubuntu OS users.
And I don' t want that there would be such user at OS !!
But shares can not be accessed from Win XP/7 clients - user credentials are
asked again and again even after right user/pass is gone to Samba4 from
clients.
And error "user in passdb, but getpwnam() fails! " is appeared in smbd.log.
I have found the following at here:
http://serverfault.com/questions/152961/user-in-passdb-but-getpwnam-fails

What could somebody recommend that make working solution ?
In case of DC Samba4 role everything work fine.
I don' t want to have user what is in Samba4 in OS !!
I want to have differentb users for different apps !!