More inquisitor fixes

One more of these.

pybuild_validate was catching Exceptions, despite not being top-level code. This meant that inquisitor wasn't aware that an Exception was raised.

Previously mods would fail to load if they made use of a pyclass and inquisitor was run in a directory not listed in repos.cfg. Now inquisitor adds the repo inside which it's run to the REPOS list if it is not already there, in addition to adding the pyclass subdirectory of the repo to sys.path.

Also fixed the ci config, as it turns out that it was subject to a race condition.