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-184/2019-05-22-0403/flakey.log

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

   https://git.samba.org/autobuild.flakey.sn-devel-184/2019-05-22-0403/samba-ad-dc-ntvfs.stderr
   https://git.samba.org/autobuild.flakey.sn-devel-184/2019-05-22-0403/samba-ad-dc-ntvfs.stdout
  
The top commit at the time of the failure was:

commit 03cbef2beff02d54063648725a71be6479886d09
Author: Andreas Schneider <asn at samba.org>
Date:   Tue Nov 6 17:22:53 2018 +0100

    lib:crypto: Remove obsolete MD5 and HMAC MD5
    
    Signed-off-by: Andreas Schneider <asn at samba.org>
    Reviewed-by: Andrew Bartlett <abartlet at samba.org>
    
    Autobuild-User(master): Andrew Bartlett <abartlet at samba.org>
    Autobuild-Date(master): Tue May 21 01:18:08 UTC 2019 on sn-devel-184

and the last 50 lines of the stdout log were:

[216(858)/253 at 23m36s] samba4.smb.signing on with -k yes --signing=required(ad_dc_ntvfs)
[217(859)/253 at 23m36s] samba4.smb.signing on with -k yes --option=gensec:fake_gssapi_krb5=yes --option=gensec:gssapi_krb5=no --signing=on(ad_dc_ntvfs)
[218(860)/253 at 23m37s] samba4.smb.signing on with -k yes --option=gensec:fake_gssapi_krb5=yes --option=gensec:gssapi_krb5=no --signing=required(ad_dc_ntvfs)
[219(861)/253 at 23m38s] samba4.smb.signing --signing=yes anon(ad_dc_ntvfs)
[220(862)/253 at 23m38s] samba4.smb.signing --signing=required anon(ad_dc_ntvfs)
[221(863)/253 at 23m38s] samba.tests.complex_expressions(ad_dc_ntvfs)
[222(885)/253 at 23m47s] samba.tests.samba_tool.gpo(ad_dc_ntvfs:local)
[223(897)/253 at 24m32s] samba.tests.dcerpc.registry(ad_dc_ntvfs:local)
[224(900)/253 at 24m32s] samba.tests.dcerpc.dnsserver(ad_dc_ntvfs)
[225(917)/253 at 24m53s] samba.tests.auth_log(ad_dc_ntvfs:local)
[226(964)/253 at 25m7s] samba.tests.auth_log_pass_change(ad_dc_ntvfs)
[227(972)/253 at 25m17s] samba.tests.auth_log_ncalrpc(ad_dc_ntvfs:local)
[228(974)/253 at 25m18s] samba.tests.auth_log_samlogon(ad_dc_ntvfs:local)
[229(975)/253 at 25m19s] samba.tests.auth_log_netlogon(ad_dc_ntvfs:local)
[230(976)/253 at 25m20s] samba.tests.auth_log_netlogon_bad_creds(ad_dc_ntvfs:local)
[231(980)/253 at 25m23s] samba.tests.password_hash_fl2008(ad_dc_ntvfs:local)
[232(984)/253 at 25m25s] samba.tests.krb5_credentials(ad_dc_ntvfs)
[233(987)/253 at 25m28s] samba.tests.py_credentials(ad_dc_ntvfs)
[234(995)/253 at 25m33s] samba.tests.emulate.traffic(ad_dc_ntvfs)
[235(997)/253 at 25m33s] samba.tests.emulate.traffic_packet(ad_dc_ntvfs)
[236(1086)/253 at 27m27s] samba.tests.blackbox.traffic_replay(ad_dc_ntvfs)
[237(1091)/253 at 28m0s] samba.tests.blackbox.traffic_learner(ad_dc_ntvfs)
[238(1093)/253 at 28m1s] samba.tests.blackbox.traffic_summary(ad_dc_ntvfs)
[239(1093)/253 at 28m2s] samba.tests.blackbox.smbcontrol(ad_dc_ntvfs:local)
[240(1095)/253 at 28m6s] samba4.urgent_replication.python(ad_dc_ntvfs)(ad_dc_ntvfs:local)
[241(1103)/253 at 28m12s] samba4.ldap.match_rules.python(ad_dc_ntvfs)
[242(1137)/253 at 28m49s] samba4.ldap.notification.python(ad_dc_ntvfs)(ad_dc_ntvfs)
UNEXPECTED(failure): samba4.ldap.notification.python(ad_dc_ntvfs).__main__.LDAPNotificationTest.test_simple_search(ad_dc_ntvfs)
REASON: Exception: Exception: Traceback (most recent call last):
  File "/memdisk/autobuild/fl/b1504522/samba-ad-dc-ntvfs/source4/dsdb/tests/python/notification.py", line 150, in test_simple_search
    self.assertIsNotNone(msg3)
AssertionError: unexpectedly None

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.raw.notify(ad_dc_ntvfs) -> 115
samba.tests.emulate.traffic_packet(ad_dc_ntvfs) -> 113
samba4.smb2.oplock(ad_dc_ntvfs) -> 103
samba4.nbt.winsreplication(ad_dc_ntvfs) -> 73
samba4.ntvfs.cifs.krb5.base.deny2(ad_dc_ntvfs) -> 60
samba4.base.deny2(ad_dc_ntvfs) -> 59
samba4.ntvfs.cifs.krb5.base.deny1(ad_dc_ntvfs) -> 54
samba4.raw.oplock(ad_dc_ntvfs) -> 54
samba4.base.deny1(ad_dc_ntvfs) -> 54
samba.tests.samba_tool.gpo(ad_dc_ntvfs:local) -> 45
ERROR: test failed with exit code 1
Makefile:16: recipe for target 'test' failed