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:

   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-09-03-1228/flakey.log

The failure seems to be in the "samba-py3" suite, whose build logs are available here:

   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-09-03-1228/samba-py3.stderr
   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-09-03-1228/samba-py3.stdout
  
The top commit at the time of the failure was:

commit 74357bf347348d3a8b7483c58e5250e98f7e8810
Author: Andrew Bartlett <abartlet at samba.org>
Date:   Sun Sep 2 18:03:06 2018 +1200

    selftest: Split up password_lockout into tests with and without a call to sleep()
    
    This means we can have a long observation window for many of the tests and
    so make them much more reliable.  Many of these cause frustrating flapping
    failures in our CI systems.
    
    Signed-off-by: Andrew Bartlett <abartlet at samba.org>
    Reviewed-by: Gary Lockyer <gary at catalyst.net.nz>
    
    Autobuild-User(master): Andrew Bartlett <abartlet at samba.org>
    Autobuild-Date(master): Mon Sep  3 06:14:55 CEST 2018 on sn-devel-144

and the last 50 lines of the stdout log were:

'+' stands for ',CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=samba,DC=example,DC=com'

SCHEMA

                                    out-of-date-ness
                     ,------------- CN=LOCALDC+
                     |   ,--------- CN=LOCALVAMPIREDC+
                DC   |   |   ,----- CN=PROMOTEDVDC+
       CN=LOCALDC+   0   -   - 
CN=LOCALVAMPIREDC+ 440   0   - 
   CN=PROMOTEDVDC+   1   -   0 

'+' stands for ',CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=samba,DC=example,DC=com'

DNSFOREST

                                    out-of-date-ness
                     ,------------- CN=LOCALDC+
                     |   ,--------- CN=LOCALVAMPIREDC+
                DC   |   |   ,----- CN=PROMOTEDVDC+
       CN=LOCALDC+   0   -   - 
CN=LOCALVAMPIREDC+ 440   0   - 
   CN=PROMOTEDVDC+   1   -   0 

'+' stands for ',CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=samba,DC=example,DC=com'
] stderr[ERROR(<class 'IndexError'>): uncaught exception - list index out of range
  File "/memdisk/autobuild/fl/b1385561/samba-py3/bin/python/samba/netcmd/__init__.py", line 183, in _run
    return self.run(*args, **kwargs)
  File "/memdisk/autobuild/fl/b1385561/samba-py3/bin/python/samba/netcmd/visualize.py", line 758, in run
    cursors = self.get_utdv(samdb, part_dn)
  File "/memdisk/autobuild/fl/b1385561/samba-py3/bin/python/samba/netcmd/visualize.py", line 697, in get_utdv
    settings_dn = str(res[0]["distinguishedName"][0])
]:

FAILED (1 failures, 0 errors and 0 unexpected successes in 0 testsuites)

A summary with detailed information can be found in:
  ./bin/ab/summary
TOP 10 slowest tests
samba.tests.samba_tool.user.python3(ad_dc_ntvfs:local) -> 85
samba.tests.samba_tool.visualize_drs.python3(vampire_dc) -> 85
samba.tests.samba_tool.user_wdigest.python3(ad_dc_ntvfs:local) -> 56
samba.tests.samba_tool.group.python3(ad_dc_ntvfs:local) -> 28
samba.tests.samba_tool.ou.python3(ad_dc_ntvfs:local) -> 27
samba.tests.dcerpc.dnsserver.python3(ad_dc_ntvfs) -> 19
samba.tests.dsdb.python3(ad_dc_ntvfs:local) -> 11
samba.tests.samba_tool.timecmd.python3(ad_dc_ntvfs:local) -> 3
samba.tests.krb5_credentials.python3(ad_dc_ntvfs) -> 3
samba.tests.gensec.python3(ad_dc_ntvfs:local) -> 3
ERROR: test failed with exit code 1