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-144/2019-04-05-0702/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-144/2019-04-05-0702/samba-ad-dc-ntvfs.stderr
   https://git.samba.org/autobuild.flakey.sn-devel-144/2019-04-05-0702/samba-ad-dc-ntvfs.stdout
  
The top commit at the time of the failure was:

commit 60e31c5556d6c409ff31a68444bebfb77f4a1869
Author: Volker Lendecke <vl at samba.org>
Date:   Mon Apr 1 15:23:11 2019 +0200

    rpc: Convert npa_tstream.c to use tstream_u32_read_send
    
    This avoids a bit of code duplication. Overall the last two commits
    add a few lines, but that also contains the header file and another GPL
    header for tstream_u32_read.c.
    
    Signed-off-by: Volker Lendecke <vl at samba.org>
    Reviewed-by: Jeremy Allison <jra at samba.org>
    
    Autobuild-User(master): Jeremy Allison <jra at samba.org>
    Autobuild-Date(master): Fri Apr  5 01:00:48 UTC 2019 on sn-devel-144

and the last 50 lines of the stdout log were:

[215(856)/252 at 20m0s] samba4.smb.signing on with -k yes --signing=on(ad_dc_ntvfs)
[216(857)/252 at 20m1s] samba4.smb.signing on with -k yes --signing=required(ad_dc_ntvfs)
[217(858)/252 at 20m2s] samba4.smb.signing on with -k yes --option=gensec:fake_gssapi_krb5=yes --option=gensec:gssapi_krb5=no --signing=on(ad_dc_ntvfs)
[218(859)/252 at 20m2s] samba4.smb.signing on with -k yes --option=gensec:fake_gssapi_krb5=yes --option=gensec:gssapi_krb5=no --signing=required(ad_dc_ntvfs)
[219(860)/252 at 20m3s] samba4.smb.signing --signing=yes anon(ad_dc_ntvfs)
[220(861)/252 at 20m3s] samba4.smb.signing --signing=required anon(ad_dc_ntvfs)
[221(862)/252 at 20m4s] samba.tests.complex_expressions(ad_dc_ntvfs)
[222(884)/252 at 20m11s] samba.tests.samba_tool.gpo(ad_dc_ntvfs:local)
[223(896)/252 at 21m0s] samba.tests.dcerpc.registry(ad_dc_ntvfs:local)
[224(899)/252 at 21m1s] samba.tests.dcerpc.dnsserver(ad_dc_ntvfs)
[225(916)/252 at 21m21s] samba.tests.auth_log(ad_dc_ntvfs:local)
[226(963)/252 at 21m57s] samba.tests.auth_log_pass_change(ad_dc_ntvfs)
[227(971)/252 at 22m6s] samba.tests.auth_log_ncalrpc(ad_dc_ntvfs:local)
[228(973)/252 at 22m7s] samba.tests.auth_log_samlogon(ad_dc_ntvfs:local)
[229(974)/252 at 22m8s] samba.tests.auth_log_netlogon(ad_dc_ntvfs:local)
[230(975)/252 at 22m9s] samba.tests.auth_log_netlogon_bad_creds(ad_dc_ntvfs:local)
[231(979)/252 at 22m12s] samba.tests.password_hash_fl2008(ad_dc_ntvfs:local)
[232(983)/252 at 22m14s] samba.tests.krb5_credentials(ad_dc_ntvfs)
[233(986)/252 at 22m16s] samba.tests.py_credentials(ad_dc_ntvfs)
[234(994)/252 at 22m22s] samba.tests.emulate.traffic(ad_dc_ntvfs)
[235(996)/252 at 22m22s] samba.tests.emulate.traffic_packet(ad_dc_ntvfs)
[236(1085)/252 at 23m57s] samba.tests.blackbox.traffic_replay(ad_dc_ntvfs)
[237(1090)/252 at 24m26s] samba.tests.blackbox.traffic_learner(ad_dc_ntvfs)
[238(1092)/252 at 24m27s] samba.tests.blackbox.traffic_summary(ad_dc_ntvfs)
[239(1092)/252 at 24m28s] samba.tests.blackbox.smbcontrol(ad_dc_ntvfs:local)
[240(1094)/252 at 24m30s] samba4.urgent_replication.python(ad_dc_ntvfs)(ad_dc_ntvfs:local)
[241(1102)/252 at 24m35s] samba4.ldap.match_rules.python(ad_dc_ntvfs)
[242(1136)/252 at 25m4s] 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/b1061585/samba-ad-dc-ntvfs/source4/dsdb/tests/python/notification.py", line 151, 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) -> 111
samba.tests.emulate.traffic_packet(ad_dc_ntvfs) -> 95
samba4.nbt.winsreplication(ad_dc_ntvfs) -> 72
samba4.ntvfs.cifs.krb5.base.deny2(ad_dc_ntvfs) -> 59
samba4.base.deny2(ad_dc_ntvfs) -> 58
samba4.ntvfs.cifs.krb5.base.deny1(ad_dc_ntvfs) -> 54
samba4.base.deny1(ad_dc_ntvfs) -> 53
samba.tests.samba_tool.gpo(ad_dc_ntvfs:local) -> 50
samba4.smb2.oplock(ad_dc_ntvfs) -> 39
samba4.raw.oplock(ad_dc_ntvfs) -> 37
ERROR: test failed with exit code 1