We've had a bit of churn recently with regard to the unit test infrastructure for SCMTools and in-progress changes. Very temporarily, unit tests could get away with not using the `test_scmtools` fixture, but only as an artifact of state leakage. Recent landed changes therefore passed at the time without this fixture, but is needed with it now, since we still need a `Tool` object in the database and we only do this if `test_scmtools` is added. This change adds this missing fixture to all tests that make use of repositories/SCMTools. It also fixes two other test failures. One was due to a copy/paste of a bad `logging.disable()` line in a new test, a copy of the problem fixed in commit 9f51ffeb3. This was causing `test_registry` to fail if run after the bad call. The other was due to a unit test using `assertQueries()` that wasn't updated for a change in `Review` accessibility checks. This has uncovered a duplicate `Q(public=True)` that may be a problem, particularly when trying to use `Q(public=False)`. This needs to be thoroughly investigated before we ship 5.0, in case there are security implications. And finally, it disables warnings in test runs due to the empty content in `test_scmtools` by preventing Django from trying to load data from this fixture in `setUpClass()`.