Here is a patch to redocument the constructor arguments. I am assuming that they were only removed by accident. The constructor arguments are already tested in ExceptionTests.testAttributes() at Lib/test/test_exceptions.py:248.

I did not restore the bit about more than three arguments being reflected in the “args” attribute, since this is not the current behaviour, and does not seem very important:

>>> OSError(1, 2, 3, 4).args
(1, 2)