Completely clear cache

def clear_cache(self):
        '''
        Completely clear cache
        '''
        errors = []
        for rdir in (self.cache_root, self.file_list_cachedir):
            if os.path.exists(rdir):
                try:
                    shutil.rmtree(rdir)
                except OSError as exc:
                    errors.append(
                        'Unable to delete {0}: {1}'.format(rdir, exc)
                    )
        return errors