[Samba] interpret non-domain users as domain users?

[d tbsky]

> On Thu, 2 May 2019 14:05:12 +0800
> if it did work, you could end up with a user called 'fred' from
> DOMAIN_A and a user called 'fred' from DOMAIN_B, so which user would be
> the one used, the one from DOMAIN_A, or the one from DOMAIN_B, or both ?

  we want this in single domain environment. it worked many years
until samba 4.7.
microsoft windows can't do it. it shows how samba open unix to windows
world, and maybe better than windows.