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-184/2019-05-27-1010/flakey.log

The failure seems to be in the "samba-nt4" suite, whose build logs are available here:

   https://git.samba.org/autobuild.flakey.sn-devel-184/2019-05-27-1010/samba-nt4.stderr
   https://git.samba.org/autobuild.flakey.sn-devel-184/2019-05-27-1010/samba-nt4.stdout
  
The top commit at the time of the failure was:

commit 412afb2aef100e09eb433b8f0cae064fc2a736b7
Author: Gary Lockyer <gary at catalyst.net.nz>
Date:   Fri May 24 11:00:05 2019 +1200

    Fix ubsan null pointer passed as argument 2
    
    Fix ubsan warning null pointer passed as argument 2 when the source
    pointer is NULL.  The calls to memcpy are now guarded by an
    if (len > 0)
    
    Signed-off-by: Gary Lockyer <gary at catalyst.net.nz>
    Reviewed-by: Andreas Schneider <asn at samba.org>
    
    Autobuild-User(master): Gary Lockyer <gary at samba.org>
    Autobuild-Date(master): Mon May 27 01:29:48 UTC 2019 on sn-devel-184

and the last 50 lines of the stdout log were:

[547(2540)/591 at 28m26s] samba.wbinfo_simple.online-status.domain=$DOMAIN(nt4_dc:local)
[548(2541)/591 at 28m26s] samba.wbinfo_simple.check-secret.domain=$DOMAIN(nt4_dc:local)
[549(2542)/591 at 28m26s] samba.wbinfo_simple.change-secret.domain=$DOMAIN(nt4_dc:local)
[550(2543)/591 at 28m27s] samba.wbinfo_simple.check-secret.domain=$DOMAIN(nt4_dc:local)
[551(2544)/591 at 28m27s] samba.wbinfo_simple.online-status.domain=$DOMAIN(nt4_dc:local)
[552(2545)/591 at 28m27s] samba.wbinfo_simple.domain-users(nt4_dc:local)
[553(2546)/591 at 28m27s] samba.wbinfo_simple.domain-groups(nt4_dc:local)
[554(2547)/591 at 28m27s] samba.wbinfo_simple.name-to-sid=$DC_USERNAME(nt4_dc:local)
[555(2548)/591 at 28m27s] samba.wbinfo_simple.name-to-sid=$DOMAIN/$DC_USERNAME(nt4_dc:local)
[556(2549)/591 at 28m27s] samba.wbinfo_simple.user-info=$DOMAIN/$DC_USERNAME(nt4_dc:local)
[557(2550)/591 at 28m28s] samba.wbinfo_simple.user-groups=$DOMAIN/$DC_USERNAME(nt4_dc:local)
[558(2551)/591 at 28m28s] samba.wbinfo_simple.authenticate=$DOMAIN/$DC_USERNAME%$DC_PASSWORD(nt4_dc:local)
[559(2552)/591 at 28m28s] samba.wbinfo_simple.allocate-uid(nt4_dc:local)
[560(2553)/591 at 28m28s] samba.wbinfo_simple.allocate-gid(nt4_dc:local)
[561(2554)/591 at 28m28s] samba.wbinfo_sids2xids.(nt4_dc:local)(nt4_dc:local)
[562(2555)/591 at 28m36s] samba.tests.ntlm_auth(nt4_dc:local)
[563(2568)/591 at 28m38s] samba.wbinfo_simple.ping(nt4_member:local)
[564(2569)/591 at 28m38s] samba.wbinfo_simple.separator(nt4_member:local)
[565(2570)/591 at 28m39s] samba.wbinfo_simple.own-domain(nt4_member:local)
[566(2571)/591 at 28m39s] samba.wbinfo_simple.all-domains(nt4_member:local)
[567(2572)/591 at 28m39s] samba.wbinfo_simple.trusted-domains(nt4_member:local)
[568(2573)/591 at 28m39s] samba.wbinfo_simple.domain-info=BUILTIN(nt4_member:local)
[569(2574)/591 at 28m39s] samba.wbinfo_simple.domain-info=$DOMAIN(nt4_member:local)
[570(2575)/591 at 28m39s] samba.wbinfo_simple.online-status(nt4_member:local)
[571(2576)/591 at 28m39s] samba.wbinfo_simple.online-status.domain=BUILTIN(nt4_member:local)
[572(2577)/591 at 28m39s] samba.wbinfo_simple.online-status.domain=$DOMAIN(nt4_member:local)
[573(2578)/591 at 28m40s] samba.wbinfo_simple.check-secret.domain=$DOMAIN(nt4_member:local)
UNEXPECTED(failure): samba.wbinfo_simple.check-secret.domain=SAMBA-TEST.wbinfo(nt4_member:local)
REASON: Exception: Exception: wbcCheckTrustCredentials(SAMBA-TEST): error code was NT_STATUS_DOMAIN_CONTROLLER_NOT_FOUND (0xc0000233)
failed to call wbcCheckTrustCredentials: WBC_ERR_AUTH_ERROR
Could not check secret
checking the trust secret for domain SAMBA-TEST via RPC calls failed

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
samba3.smb2.lease(nt4_dc) -> 160
samba3.raw.notify(nt4_dc) -> 105
samba3.smb2.oplock(nt4_dc) -> 104
samba3.smb2.notify(nt4_dc) -> 83
samba3.blackbox.net.rpc.conf(nt4_dc) -> 72
samba3.rpc.samr.passwords.lockout(nt4_dc) -> 62
samba4.rpc.echo on ncacn_np with object(nt4_dc) -> 61
samba3.base.dir2(nt4_dc) -> 52
samba3.smb2.compound_find(nt4_dc) -> 51
samba3.smb2.compound_find(nt4_dc) -> 48
ERROR: test failed with exit code 1
Makefile:16: recipe for target 'test' failed