The test "test_normalization" download a file from the "unicode.org" website and keep it in the local cache "Lib/test/data/" directory for next runs.
On test setup, it verifies if the 1st line contains the right version "unicodedata.unidata_version".
It should unlink the file if it is outdated.
But it does not work as expected: it looks for the file in the wrong directory.

~ $ echo "# NormalizationTest-3.0.0.txt ~ outdated version" > Lib/test/data/NormalizationTest.txt

~ $ ./python -m test.regrtest -uall test_normalization
test_normalization
test test_normalization failed -- Traceback (most recent call last):
  File "./Lib/test/test_normalization.py", line 96, in test_main
    self.assertTrue(X == NFC(X) == NFD(X) == NFKC(X) == NFKD(X), c)
AssertionError: 160

1 test failed:
    test_normalization

~ $ cat Lib/test/data/NormalizationTest.txt
# NormalizationTest-3.0.0.txt ~ outdated version