Code review comment for ~kissiel/checkbox-support:fix-missing-reqs

I've managed to reproduce this, and it is a legitimate failure. If I revert it, it no longer fails.

Requests requires 'chardet>=3.0.2,<3.1.0', but the xenial base systems has chardet 2.3.0 installed from deb. Since the tests run directly in the container and not in a venv, it picks up the package version which is too old.