The resolution of file timestamps is different in ZFS to tmpfs, so the comparison fails with an error like: AssertionError: 1686679063.0 not greater than or equal to 1686679063.8400018 Convert both timestamps to integer before comparing. diff -wpruN --no-dereference '--exclude=*.orig' a~/Lib/test/test_tarfile.py a/Lib/test/test_tarfile.py --- a~/Lib/test/test_tarfile.py 1970-01-01 00:00:00 +++ a/Lib/test/test_tarfile.py 1970-01-01 00:00:00 @@ -3299,7 +3299,7 @@ class NoneInfoExtractTests(ReadTest): if not path.is_symlink(): raise else: - self.assertGreaterEqual(path.stat().st_mtime, now) + self.assertGreaterEqual(int(path.stat().st_mtime), int(now)) def test_extractall_none_mode(self): # modes of directories and regular files should match the mode