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-144/2018-12-07-1335/flakey.log

The failure seems to be in the "samba-none-env" suite, whose build logs are available here:

   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-12-07-1335/samba-none-env.stderr
   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-12-07-1335/samba-none-env.stdout
  
The top commit at the time of the failure was:

commit d5f9bc45e22d687c03d77afe9ada21ed79366df3
Author: Daniel Southward-Ellis <danielsouthwardellis at catalyst.net.nz>
Date:   Mon Dec 3 14:42:14 2018 +1300

    Removed dead groups link from Mail List Etiquette
    
    Signed-off-by: Daniel Southward-Ellis <danielsouthwardellis at catalyst.net.nz>
    Reviewed-by: Andrew Bartlett <abartlet at samba.org>
    Reviewed-by: Jeremy Allison <jra at samba.org>
    
    Autobuild-User(master): Andrew Bartlett <abartlet at samba.org>
    Autobuild-Date(master): Fri Dec  7 10:12:42 CET 2018 on sn-devel-144

and the last 50 lines of the stdout log were:

[109(1746)/218 at 31m46s] samba4.local.strlist
[110(1775)/218 at 31m46s] samba4.local.file
[111(1777)/218 at 31m46s] samba4.local.str
[112(1784)/218 at 31m46s] samba4.local.time
[113(1788)/218 at 31m46s] samba4.local.datablob
[114(1794)/218 at 31m46s] samba4.local.binsearch
[115(1796)/218 at 31m46s] samba4.local.asn1
[116(1801)/218 at 31m47s] samba4.local.anonymous_shared
[117(1802)/218 at 31m47s] samba4.local.strv
[118(1806)/218 at 31m47s] samba4.local.strv_util
[119(1808)/218 at 31m47s] samba4.local.util
[120(1810)/218 at 31m47s] samba4.local.idtree
[121(1811)/218 at 31m47s] samba4.local.dlinklist
[122(1812)/218 at 31m47s] samba4.local.genrand
[123(1814)/218 at 31m47s] samba4.local.iconv
[124(1819)/218 at 32m8s] samba4.local.socket
[125(1821)/218 at 32m8s] samba4.local.pac
[126(1823)/218 at 32m8s] samba4.local.resolve
[127(1825)/218 at 32m10s] samba4.local.sddl
[128(1843)/218 at 32m10s] samba4.local.ndr
[129(2095)/218 at 32m11s] samba4.local.tdr
[130(2104)/218 at 32m11s] samba4.local.share
[131(2111)/218 at 32m11s] samba4.local.loadparm
[132(2134)/218 at 32m12s] samba4.local.charset
[133(2156)/218 at 32m15s] samba4.local.convert_string_handle
[134(2164)/218 at 32m17s] samba4.local.convert_string
[135(2167)/218 at 32m17s] samba4.local.string_case_handle
[136(2172)/218 at 32m20s] samba4.local.string_case_handle
[137(2177)/218 at 32m20s] samba4.local.compression
[138(2178)/218 at 32m22s] samba4.local.event
backend 'poll_mt' - test_event_fd1
UNEXPECTED(failure): samba4.local.event.fd1(none)
REASON: Exception: Exception: ../../lib/tevent/testsuite.c:451: Expression `state.error == ((void *)0)' failed: ../../lib/tevent/testsuite.c:348

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
samba.tests.docs -> 520
samba4.blackbox.upgradeprovision.release-4-0-0 -> 198
samba4.blackbox.upgradeprovision.alpha13 -> 195
samba4.blackbox.schemaupgrade -> 162
samba4.blackbox.dbcheck.release-4-0-0 -> 119
samba4.blackbox.dbcheck.release-4-1-0rc3 -> 106
ldb.python -> 90
samba4.blackbox.dbcheck.alpha13 -> 85
samba4.blackbox.functionalprep -> 84
samba4.blackbox.dbcheck.release-4-1-6-partial-object -> 68
ERROR: test failed with exit code 1