autobuild[sn-devel-144]: intermittent test failure detected

[autobuild]

The autobuild test system (on sn-devel-144) has detected an intermittent failing test in 
the current master tree.

The autobuild log of the failure is available here:

   http://git.samba.org/autobuild.flakey.sn-devel-144/2017-09-26-1357/flakey.log

The samba build logs are available here:

   http://git.samba.org/autobuild.flakey.sn-devel-144/2017-09-26-1357/samba.stderr
   http://git.samba.org/autobuild.flakey.sn-devel-144/2017-09-26-1357/samba.stdout
  
The top commit at the time of the failure was:

commit 0d4c3e5e3fd379b35645d5d10f9705116eba4197
Author: Tim Beale <timbeale at catalyst.net.nz>
Date:   Thu Sep 14 16:34:59 2017 +1200

    replmd: RMD_VERSION incorrectly incremented for link conflicts
    
    This problem was noticed when 2 DCs added the same linked attribute at
    roughly the same time. One DC would have a later timestamp than the
    other, so it would re-apply the same link information. However, when it
    did this, replmd_update_la_val() would incorrectly increment the
    RMD_VERSION for the attribute. We then end up with one DC having a
    higher RMD_VERSION than the others (and it doesn't replicate the new
    RMD_VERSION out).
    
    During replication RMD_VERSION is used to determine whether a linked
    attribute is old (and should be ignored), or whether the information is
    new and should be applied to the DB. This RMD_VERSION discrepancy could
    potentially cause a subsequent linked attribute update to be ignored.
    
    Normally when a local DB operation is performed, we just pass in a
    version of zero and get replmd_update_la_val() to increment what's
    already in the DB. However, we *never* want this to happen during
    replication - we should always use the version we receive from the peer
    DC.
    
    This patch fixes the problem by separating the API into two:
    - replmd_update_la_val(): we're updating a linked attribute in the DB,
      and so as part of this operation we always want to increment the
      version number (the version no longer need to be passed in because
      we can work it out from the existing DB entry).
    - replmd_set_la_val(): we want to set a linked attribute to use the
      exact values we're telling it, including the version. This is what
      replication needs to use.
    
    BUG: https://bugzilla.samba.org/show_bug.cgi?id=13038
    Signed-off-by: Tim Beale <timbeale at catalyst.net.nz>
    Reviewed-by: Andrew Bartlett <abartlet at samba.org>
    Reviewed-by: Douglas Bagnall <douglas.bagnall at catalyst.net.nz>
    
    Autobuild-User(master): Andrew Bartlett <abartlet at samba.org>
    Autobuild-Date(master): Tue Sep 26 09:36:48 CEST 2017 on sn-devel-144