def clear(self, youngest_rev=None):
        self.youngest = None
        if youngest_rev is not None:
            self.youngest = self.normalize_rev(youngest_rev)
        self.oldest = None
Tests the path specification comparable property.
dataset/ETHPy150Open edgewall/trac/tracopt/versioncontrol/svn/svn_fs.py/SubversionRepository.clear--crossover with--dataset/ETHPy150Open log2timeline/dfvfs/tests/path/ntfs_path_spec.py/NTFSPathSpecTest.testComparable