Seen on master, commit cf7efe01e791fd1aa688624194e6e2ffffd8f97f

See the attached logs for details of what went wrong and an attempt at providing some debug info from the core.

SCTP fails with VPP regular build (does not produce a core), but crashes with debug build (produces a core).

Regular build:
==============================================================================
SCTP Test Case
==============================================================================
SCTP echo client/server transfer ERROR [ temp dir used by test case: /tmp/vpp-unittest-TestSCTP-VBqz8Y ]

==============================================================================
ERROR: SCTP echo client/server transfer
------------------------------------------------------------------------------
Traceback (most recent call last):
File "/home/jlinkes/vpp/test/test_sctp.py", line 75, in test_sctp_transfer
" uri " + uri)
File "/home/jlinkes/vpp/test/vpp_papi_provider.py", line 191, in cli
r = self.papi.cli_inband(length=len(cli), cmd=cli)
File "build/bdist.linux-aarch64/egg/vpp_papi/vpp_papi.py", line 106, in _call_
return self._func(**kwargs)
File "build/bdist.linux-aarch64/egg/vpp_papi/vpp_papi.py", line 397, in f
return self._call_vpp(i, msg, multipart, **kwargs)
File "build/bdist.linux-aarch64/egg/vpp_papi/vpp_papi.py", line 602, in _call_vpp
msg = self._read()
File "build/bdist.linux-aarch64/egg/vpp_papi/vpp_papi.py", line 442, in _read
raise IOError(rv, 'vac_read failed')
IOError: [Errno -1] vac_read failed

==============================================================================
ERROR: SCTP echo client/server transfer
------------------------------------------------------------------------------
Traceback (most recent call last):
File "/home/jlinkes/vpp/test/test_sctp.py", line 43, in tearDown
i.set_table_ip4(0)
File "/home/jlinkes/vpp/test/vpp_interface.py", line 297, in set_table_ip4
self.sw_if_index, 0, self.ip4_table_id)
File "/home/jlinkes/vpp/test/vpp_papi_provider.py", line 242, in sw_interface_set_table
'vrf_id': table_id})
File "/home/jlinkes/vpp/test/vpp_papi_provider.py", line 160, in api
reply = api_fn(**api_args)
File "build/bdist.linux-aarch64/egg/vpp_papi/vpp_papi.py", line 106, in _call_
return self._func(**kwargs)
File "build/bdist.linux-aarch64/egg/vpp_papi/vpp_papi.py", line 397, in f
return self._call_vpp(i, msg, multipart, **kwargs)
File "build/bdist.linux-aarch64/egg/vpp_papi/vpp_papi.py", line 602, in _call_vpp
msg = self._read()
File "build/bdist.linux-aarch64/egg/vpp_papi/vpp_papi.py", line 442, in _read
raise IOError(rv, 'vac_read failed')
IOError: [Errno -1] vac_read failed

Debug build:
==============================================================================
SCTP Test Case
==============================================================================
08:53:54,687 Child python process unresponsive and core-file exists in test temporary directory!
08:53:54,689 Creating a link to the failed test: /tmp/vpp-failed-unittests/vpp-unittest-TestSCTP-FTib6D-FAILED -> vpp-unittest-TestSCTP-FTib6D
08:53:54,690 Copying api_post_mortem.31016 to /tmp/vpp-unittest-TestSCTP-FTib6D
08:53:54,691 Core-file exists in test temporary directory: /tmp/vpp-unittest-TestSCTP-FTib6D/core!