python-cheroot two failing tests "unpack requires a string argument of length 12" for ppc64le

The failure is reported since 20190306 as per jobhist output,
so most probably since enabling of testsuite.
===
$osc jobhist  devel:languages:python/python-cheroot openSUSE_Factory_PowerPC ppc64le
time                 package        reason           code      build time      worker
2019-02-15 04:32:04  python-cheroot meta change      unchanged 1m 34s   obs-power8-03:12
...
2019-03-05 01:41:07  python-cheroot meta change      unchanged 1m 52s   obs-power8-03:19
2019-03-06 11:01:05  python-cheroot source change    failed    2m 34s   obs-power8-05:3
2019-03-07 17:32:53  python-cheroot meta change      failed    2m 33s   obs-power8-05:20
...
2019-08-21 19:32:34  python-cheroot meta change      failed    1m 52s   obs-power8-03:20
2019-08-22 13:52:34  python-cheroot meta change      failed    3m 40s   obs-power8-07:5
===

extract from build log https://build.opensuse.org/package/live_build_log/devel:languages:python/python-cheroot/openSUSE_Factory_PowerPC/ppc64le
===
[  171s] cheroot/test/test_server.py::test_peercreds_unix_sock FAILED             [ 88%]
[  171s] cheroot/test/test_server.py::test_peercreds_unix_sock_with_lookup FAILED [ 89%]
...
[  177s] ___________________________ test_peercreds_unix_sock _
...
[  177s] E           HTTPError: 500 Server Error: Internal Server Error for url: http+unix://%2Ftmp%2Ftmp3WSNw9/peer_creds/ids
...
[  177s]   File "/home/abuild/rpmbuild/BUILD/cheroot-6.5.5/cheroot/server.py", line 1399, in get_peer_creds
[  177s]     pid, uid, gid = struct.unpack(PEERCRED_STRUCT_DEF, peer_creds)
[  177s] error: unpack requires a string argument of length 12
[  177s] _____________________ test_peercreds_unix_sock_with_lookup _
...
[  177s] E           HTTPError: 500 Server Error: Internal Server Error for url: http+unix://%2Ftmp%2FtmpVe2REm/peer_creds/texts
...
[  177s]   File "/home/abuild/rpmbuild/BUILD/cheroot-6.5.5/cheroot/server.py", line 1399, in get_peer_creds
[  177s]     pid, uid, gid = struct.unpack(PEERCRED_STRUCT_DEF, peer_creds)
[  177s] error: unpack requires a string argument of length 12
[  177s] == 2 failed, 70 passed, 1 skipped, 30 deselected, 3 xfailed in 43.27 seconds ===
[  177s] error: Bad exit status from /var/tmp/rpm-tmp.C8h9wf (%check)
===

I do not know how to investigate.