When running Python's test suite, no warnings should result when you run it
under :ref:`strenuous testing conditions <strenuous_testing>` (you can ignore
the extra flags passed to test that cause randomness and parallel execution
if you want). Unfortunately new warnings are added to Python on occasion which
take some time to eliminate (e.g., ResourceWarning). Typically the easy
warnings are dealt with quickly, but the more difficult ones that require some
thought and work do not get fixed immediately.
If you decide to tackle a warning you have found, open an issue on the issue tracker (if one has not already been opened) and say you are going to try and tackle the issue, and then proceed to fix the issue.