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-144/2018-11-23-1852/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-144/2018-11-23-1852/samba-py3.stderr
   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-11-23-1852/samba-py3.stdout
  
The top commit at the time of the failure was:

commit fabc3c9d3827fd30d7cec674105218c97c04e801
Author: Tim Beale <timbeale at catalyst.net.nz>
Date:   Thu Nov 22 10:35:01 2018 +1300

    source4 smbd prefork: Add code comments
    
    Add some comments to the prefork code explaining what's going on.
    
    Signed-off-by: Tim Beale <timbeale at catalyst.net.nz>
    Reviewed-by: Andrew Bartlett <abartlet at samba.org>
    
    Autobuild-User(master): Andrew Bartlett <abartlet at samba.org>
    Autobuild-Date(master): Fri Nov 23 11:40:49 CET 2018 on sn-devel-144

and the last 50 lines of the stdout log were:

[27(202)/78 at 6m10s] samba.tests.py_credentials.python3(promoted_dc)
[28(210)/78 at 7m0s] samba.tests.emulate.traffic.python3(ad_dc_ntvfs)
[29(212)/78 at 7m1s] samba.tests.emulate.traffic_packet.python3(ad_dc_ntvfs)
[30(301)/78 at 8m45s] samba.tests.blackbox.traffic_replay.python3(ad_dc_ntvfs)
[31(307)/78 at 9m3s] samba.tests.blackbox.traffic_learner.python3(ad_dc_ntvfs)
[32(309)/78 at 9m4s] samba.tests.blackbox.traffic_summary.python3(ad_dc_ntvfs)
[33(309)/78 at 9m4s] samba.tests.blackbox.smbcontrol.python3(ad_dc_ntvfs:local)
[34(311)/78 at 9m6s] samba.tests.blackbox.smbcontrol.python3(promoted_dc:local)
[35(313)/78 at 9m8s] samba4.schemaInfo.python(ad_dc_ntvfs).python3(ad_dc_ntvfs)
[36(315)/78 at 9m12s] samba.tests.dsdb_schema_attributes.python3(ad_dc_ntvfs:local)
[37(321)/78 at 9m31s] samba4.drs.replica_sync_rodc.python(rodc).python3(rodc:local)
[38(323)/78 at 10m20s] samba4.ldap.passwordsettings.python.python3(ad_dc_ntvfs)
[39(335)/78 at 11m13s] samba4.tombstone_reanimation.python.python3(ad_dc_ntvfs)
[40(347)/78 at 11m21s] samba.tests.upgradeprovisionneeddc.python3(ad_dc_ntvfs:local)
[41(358)/78 at 11m24s] samba.tests.samba_tool.rodc.python3(rodc:local)
[42(367)/78 at 12m4s] samba4.drs.ridalloc_exop.python(vampire_dc).python3(vampire_dc)
[43(378)/78 at 15m12s] samba4.drs.samba_tool_drs.python(vampire_dc).python3(vampire_dc:local)
[44(392)/78 at 17m12s] samba4.drs.samba_tool_drs_showrepl.python(vampire_dc).python3(vampire_dc:local)
[45(396)/78 at 17m28s] samba4.drs.replica_sync.python(vampire_dc).python3(vampire_dc:local)
[46(412)/78 at 19m7s] samba4.drs.delete_object.python(vampire_dc).python3(vampire_dc)
[47(414)/78 at 19m16s] samba4.drs.fsmo.python(vampire_dc).python3(vampire_dc)
[48(419)/78 at 19m28s] samba4.drs.repl_move.python(vampire_dc).python3(vampire_dc)
[49(440)/78 at 22m18s] samba4.drs.getnc_exop.python(vampire_dc).python3(vampire_dc)
[50(452)/78 at 22m29s] samba4.drs.getnc_unpriv.python(vampire_dc).python3(vampire_dc)
[51(456)/78 at 22m35s] samba4.drs.link_conflicts.python(vampire_dc).python3(vampire_dc)
[52(468)/78 at 24m49s] samba4.drs.samba_tool_drs.python(promoted_dc).python3(promoted_dc:local)
UNEXPECTED(error): samba4.drs.samba_tool_drs.python(promoted_dc).python3.samba_tool_drs.SambaToolDrsTests.test_samba_tool_kcc(promoted_dc:local)
REASON: Exception: Exception: Traceback (most recent call last):
  File "/memdisk/autobuild/fl/b2630714/samba-py3/source4/torture/drs/python/samba_tool_drs.py", line 81, in test_samba_tool_kcc
    self.cmdline_creds))
  File "bin/python/samba/tests/__init__.py", line 424, in check_output
    raise BlackboxProcessError(retcode, line, stdoutdata, stderrdata)
samba.tests.BlackboxProcessError: Command '/memdisk/autobuild/fl/b2630714/samba-py3/bin/samba-tool drs kcc localdc -USAMBADOMAIN/Administrator%locDCpass1'; shell True; exit status 255; stdout: 'b'''; stderr: 'b"ERROR(runtime): DsExecuteKCC failed - (3221225653, '{Device Timeout} The specified I/O operation on %hs was not completed before the time-out period expired.')\n"'

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

A summary with detailed information can be found in:
  ./bin/ab/summary
TOP 10 slowest tests
samba4.drs.ridalloc_exop.python(vampire_dc).python3(vampire_dc) -> 188
samba4.drs.repl_move.python(vampire_dc).python3(vampire_dc) -> 169
samba4.drs.link_conflicts.python(vampire_dc).python3(vampire_dc) -> 134
samba4.drs.samba_tool_drs.python(vampire_dc).python3(vampire_dc:local) -> 120
samba.tests.emulate.traffic_packet.python3(ad_dc_ntvfs) -> 104
samba4.drs.replica_sync.python(vampire_dc).python3(vampire_dc:local) -> 99
samba.tests.samba_tool.user.python3(ad_dc_ntvfs:local) -> 72
samba4.ldap.passwordsettings.python.python3(ad_dc_ntvfs) -> 53
samba.tests.samba_tool.user_wdigest.python3(ad_dc_ntvfs:local) -> 41
samba.tests.samba_tool.rodc.python3(rodc:local) -> 39
ERROR: test failed with exit code 1