Set lockfile path as to whether or not the system is indexing.
        NOT THREAD SAFE, USE ONLY FOR CRASH DETECTION.

def db_set_indexing(cls, is_indexing, impl, working_dir):
        """
        Set lockfile path as to whether or not the system is indexing.
        NOT THREAD SAFE, USE ONLY FOR CRASH DETECTION.
        """
        indexing_lockfile_path = config.get_lockfile_filename(impl, working_dir)
        if is_indexing:
            # make sure this exists
            with open(indexing_lockfile_path, 'w') as f:
                pass

        else:
            # make sure it does not exist 
            try:
                os.unlink(indexing_lockfile_path)
            except:
                pass