Tests fail in mock env : unable to import BuildRequires Python module

[Dan Scott]

Per https://bugzilla.redhat.com/show_bug.cgi?id=1070074 I'm working on
updating python-rdflib to 4.1.1, but currently having trouble with a
new dependency on python-html5lib.

The problem is that running a mock build fails as a few tests claim
they were unable to import html5lib; this is perfectly consistent with
what I see when I run nosetests in a local rdflib source tree and
python-html5lib has not been installed. When I then install
python-html5lib and run nosetests locally, those tests pass.

The puzzling part is that the mock log shows that python-html5lib _is_
getting installed, so the html5lib module should be available to the
tests.

Does anyone have an idea of why the installed html5lib module isn't
being found in the mock environment?

Thanks,
Dan