[ALUG] When using Samba 4 as AD do NOT update to samba 4.8.x

[Andreas Tauscher]

Got this today from the SerNet mailinglist:

It turned out that under certain circumstances, updating Samba AD DCs to
Samba 4.8.x might lead to completely broken domain controllers!

For more details, please see
https://bugzilla.samba.org/show_bug.cgi?id=13335

In the case of a broken 4.8 DC, please note that downgrading to older
versions requires to run the 'sambaundoguididx' script to undo a GUID
index. This script allows to re-index the Samba AD database, in order
downgrade from version 4.8 to 4.7.

Fileservers are not affected by this issue and setting up new 4.8.x
domain controllers works fine also.