swh.core [2] changed the remote exception serialization handling.
So the current build [1] is broken. It needs adaptation to retrieve the
exception information at its first level. This adapts accordingly the failing
tests.
[1] https://jenkins.softwareheritage.org/job/DVAU/job/tests/881/
[2] Related to D4515 (released in swh.core 0.9.0)