$ ./python -S Lib/test/test_site.py 
Traceback (most recent call last):
  File "Lib/test/test_site.py", line 28, in <module>
    raise unittest.SkipTest("importation of site.py suppressed")
unittest.case.SkipTest: importation of site.py suppressed

This counts as fail test. So when you execute the whole unit test:

$ ./python -S Lib/test

You'll get 2 fail tests.

The first one is test_trace, already fixed in #19398, but not yet committed.

The second one is this one, test_site.

'raise unittest.SkipTest("importation of site.py suppressed")' will make the file counts as fail test.

Attached the patch to make it does not count as fail test.