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.