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-144/2018-06-29-0624/flakey.log

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

   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-06-29-0624/samba.stderr
   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-06-29-0624/samba.stdout
  
The top commit at the time of the failure was:

commit 396f123121ddb290f4a5536a2224aa4a651c072f
Author: Björn Baumbach <bb at sernet.de>
Date:   Wed Jun 27 14:20:40 2018 +0200

    README.Coding: Fix link to Python coding style guide (PEP 8)
    
    Signed-off-by: Björn Baumbach <bb at sernet.de>
    Reviewed-by: David Mulder <dmulder at suse.com>
    
    Autobuild-User(master): Björn Baumbach <bbaumbach at samba.org>
    Autobuild-Date(master): Thu Jun 28 15:04:44 CEST 2018 on sn-devel-144

and the last 50 lines of the stdout log were:

[70(148)/855 at 4m14s] samba3.blackbox.smbclient_ntlm.plain (maptoguest)(maptoguest)
[71(161)/855 at 4m15s] samba3.raw.samba3hide(simpleserver)
[72(162)/855 at 4m15s] samba3.raw.samba3checkfsp(simpleserver)
[73(163)/855 at 4m16s] samba3.raw.samba3closeerr(simpleserver)
[74(164)/855 at 4m16s] samba3.smb2.change_notify_disabled(simpleserver)
[75(165)/855 at 4m16s] samba3.smb2.dosmode(simpleserver)
[76(166)/855 at 4m16s] samba3.rpc.schannel_anon_setpw anonymous password set (schannel enforced server-side)(nt4_dc_schannel)
[77(167)/855 at 4m16s] idmap.rfc2307(ad_member_rfc2307)
[78(326)/855 at 4m57s] idmap.alloc(ad_member_rfc2307)
[79(328)/855 at 4m57s] samba3.rpc.lsa.lookupsids krb5 with old ccache ncacn_np with [smb2] (ktest)
[80(329)/855 at 4m57s] samba3.rpc.lsa.lookupsids krb5 ncacn_np with [smb2] (ktest)
[81(330)/855 at 4m58s] samba3.blackbox.rpcclient krb5 ncacn_np with [krb5] (ktest:local)
[82(331)/855 at 4m58s] samba3.blackbox.rpcclient krb5 ncacn_np with [spnego,krb5] (ktest:local)
[83(332)/855 at 4m58s] samba3.rpc.lsa.lookupsids krb5 with old ccache ncacn_np with [smb2,connect] (ktest)
[84(333)/855 at 4m58s] samba3.rpc.lsa.lookupsids krb5 ncacn_np with [smb2,connect] (ktest)
[85(334)/855 at 4m58s] samba3.blackbox.rpcclient krb5 ncacn_np with [krb5,connect] (ktest:local)
[86(335)/855 at 4m58s] samba3.blackbox.rpcclient krb5 ncacn_np with [spnego,krb5,connect] (ktest:local)
[87(336)/855 at 4m58s] samba3.rpc.lsa.lookupsids krb5 with old ccache ncacn_np with [smb2,packet] (ktest)
[88(337)/855 at 4m59s] samba3.rpc.lsa.lookupsids krb5 ncacn_np with [smb2,packet] (ktest)
[89(338)/855 at 4m59s] samba3.blackbox.rpcclient krb5 ncacn_np with [krb5,packet] (ktest:local)
[90(339)/855 at 4m59s] samba3.blackbox.rpcclient krb5 ncacn_np with [spnego,krb5,packet] (ktest:local)
[91(340)/855 at 4m59s] samba3.rpc.lsa.lookupsids krb5 with old ccache ncacn_np with [smb2,sign] (ktest)
[92(341)/855 at 4m59s] samba3.rpc.lsa.lookupsids krb5 ncacn_np with [smb2,sign] (ktest)
[93(342)/855 at 4m59s] samba3.blackbox.rpcclient krb5 ncacn_np with [krb5,sign] (ktest:local)
[94(343)/855 at 5m0s] samba3.blackbox.rpcclient krb5 ncacn_np with [spnego,krb5,sign] (ktest:local)
[95(344)/855 at 5m0s] samba3.rpc.lsa.lookupsids krb5 with old ccache ncacn_np with [smb2,seal] (ktest)
[96(345)/855 at 5m0s] samba3.rpc.lsa.lookupsids krb5 ncacn_np with [smb2,seal] (ktest)
[97(346)/855 at 5m0s] samba3.blackbox.rpcclient krb5 ncacn_np with [krb5,seal] (ktest:local)
[98(347)/855 at 5m0s] samba3.blackbox.rpcclient krb5 ncacn_np with [spnego,krb5,seal] (ktest:local)
[99(348)/855 at 5m0s] samba3.blackbox.sharesec(simpleserver:local)
[100(383)/855 at 5m2s] samba3.blackbox.net_tdb(simpleserver:local)
UNEXPECTED(failure): samba3.blackbox.net_tdb.Looking for open file in locking.tdb(simpleserver:local)
REASON: Exception: Exception: Invalid length of key

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.smbtorture_s3.vfs_aio_fork(simpleserver).RW2(simpleserver) -> 136
idmap.rfc2307(ad_member_rfc2307) -> 34
samba3.smbtorture_s3.plain(ad_dc_ntvfs).LOCK1(ad_dc_ntvfs) -> 11
samba3.smbtorture_s3.plain(ad_dc_ntvfs).IOCTL(ad_dc_ntvfs) -> 6
samba3.smbtorture_s3.plain(ad_dc_ntvfs).TRANS2(ad_dc_ntvfs) -> 6
samba3.smbtorture_s3.vfs_aio_fork(simpleserver).RW1(simpleserver) -> 5
samba3.smbtorture_s3.plain(ad_dc_ntvfs).OPLOCK1(ad_dc_ntvfs) -> 4
samba3.smbtorture_s3.plain(ad_dc_ntvfs).RW2(ad_dc_ntvfs) -> 2
samba3.blackbox.sharesec(simpleserver:local) -> 2
samba3.smbtorture_s3.vfs_aio_pthread(simpleserver).RW2(simpleserver) -> 2
ERROR: test failed with exit code 1