autobuild[sn-devel-184]: intermittent test failure detected

[autobuild]

The autobuild test system (on sn-devel-184) 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-184/2019-07-17-2138/flakey.log

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

   https://git.samba.org/autobuild.flakey.sn-devel-184/2019-07-17-2138/samba-schemaupgrade.stderr
   https://git.samba.org/autobuild.flakey.sn-devel-184/2019-07-17-2138/samba-schemaupgrade.stdout
  
The top commit at the time of the failure was:

commit 69cca061a4e176c3d23f5f0771893011adafc940
Author: Volker Lendecke <vl at samba.org>
Date:   Wed May 1 15:34:22 2019 +0200

    lib: Optimize file_compare
    
    Triggered by two coverity false positives. Loading both files into
    talloc'ed memory seems inefficient to me. Rely on stdio to do proper
    buffering. This removes the restriction from ae95d611: "It is meant for
    small files".
    
    This is more lines, but to me it has less implicit complexity.
    
    Signed-off-by: Volker Lendecke <vl at samba.org>
    Reviewed-by: Uri Simchoni <uri at samba.org>
    
    Autobuild-User(master): Uri Simchoni <uri at samba.org>
    Autobuild-Date(master): Wed Jul 17 12:45:51 UTC 2019 on sn-devel-184

and the last 50 lines of the stdout log were:

Applying Sch67.ldf updates...
5 changes applied
Applying Sch68.ldf updates...
30 changes applied
Applying Sch69.ldf updates...
4 changes applied
Schema successfully updated
Replicate from liveupgrade1dc to liveupgrade2dc was successful.
[1(0)/11 at 0s] samba.tests.samba_tool.schema(schema_dc:local)
[2(4)/11 at 2m36s] samba4.schemaInfo.python(schema_dc:local)(schema_dc:local)
[3(7)/11 at 2m42s] samba.tests.dsdb_schema_attributes(schema_dc:local)
[4(13)/11 at 3m0s] samba4.ldap_schema.python(schema_dc)(schema_dc)
[5(39)/11 at 3m39s] samba4.ldap.possibleInferiors.python(schema_dc)(schema_dc)
[6(313)/11 at 3m41s] samba4.ldap.secdesc.python(schema_dc)(schema_dc)
[7(396)/11 at 6m33s] samba4.ldap.acl.python(schema_dc)(schema_dc)
[8(449)/11 at 7m35s] samba4.ldap.passwords.python(schema_dc)(schema_dc)
[9(467)/11 at 7m57s] samba4.drs.samba_tool_drs.python(schema_pair_dc)(schema_pair_dc:local)
[10(481)/11 at 10m2s] samba4.drs.getnc_schema.python(schema_pair_dc)(schema_pair_dc)
Failed repl, retrying in 10s
UNEXPECTED(failure): samba4.drs.getnc_schema.python(schema_pair_dc).getnc_schema.SchemaReplicationTests.test_schema_linked_attributes(schema_pair_dc)
REASON: Exception: Exception: Traceback (most recent call last):
  File "/memdisk/autobuild/fl/b761695/samba-schemaupgrade/source4/torture/drs/python/getnc_schema.py", line 290, in test_schema_linked_attributes
    self.do_repl(self.schema_dn)
  File "/memdisk/autobuild/fl/b761695/samba-schemaupgrade/source4/torture/drs/python/getnc_schema.py", line 66, in do_repl
    self.assertCmdSuccess(result, out, err)
  File "bin/python/samba/tests/samba_tool/base.py", line 109, in assertCmdSuccess
    exit, out, err, msg))
AssertionError: -1 is not None : exit[-1] stdout[] stderr[ERROR(<class 'samba.drs_utils.drsException'>): DsReplicaSync failed - drsException: DsReplicaSync failed (1168, 'WERR_NOT_FOUND')
  File "bin/python/samba/netcmd/drs.py", line 575, in run
    drs_utils.sendDsReplicaSync(server_bind, server_bind_handle, source_dsa_guid, NC, req_options)
  File "bin/python/samba/drs_utils.py", line 92, in sendDsReplicaSync
    raise drsException("DsReplicaSync failed %s" % estr)
]:

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
samba4.ldap.secdesc.python(schema_dc)(schema_dc) -> 173
samba4.drs.samba_tool_drs.python(schema_pair_dc)(schema_pair_dc:local) -> 125
samba4.ldap.acl.python(schema_dc)(schema_dc) -> 62
samba4.ldap_schema.python(schema_dc)(schema_dc) -> 39
samba4.ldap.passwords.python(schema_dc)(schema_dc) -> 22
samba.tests.dsdb_schema_attributes(schema_dc:local) -> 18
samba.tests.samba_tool.schema(schema_dc:local) -> 12
samba4.schemaInfo.python(schema_dc:local)(schema_dc:local) -> 5
samba4.ldap.possibleInferiors.python(schema_dc)(schema_dc) -> 2
ERROR: test failed with exit code 1
Makefile:16: recipe for target 'test' failed