The fix only affects the error message of __class__ assignment. CID 983564

sizeof(Py_ssize_t *) == sizeof(Py_ssize_t) but it's not a portable assumption.
CID 486403

CID 486616, CID 486617, CID 486615

Before this change only the methods were _single_underscored_; now
the attributes are as well.

I tested the patch manually by injecting a fault using gdb: list items are
correctly restored on failure.

The docs also clarify the 'Interesting Example' duplicate-free enum is for
demonstration purposes.

follow_symlinks=False whereas the fchmodat() function is not avaialble.

whereas the fchmodat() function is not avaialble.

functions if a Python exception was raised

handler if a Python exception is set

Modules/python.c:40: warning: ISO C90 forbids mixed declarations and code

Don't call PyErr_NewException() if an exception is set, or type_call() would
fail with an assertion error.

assertion error if they are called with an exception set (PyErr_Occurred()).

As PyEval_EvalFrameEx(), they may clear the current exception and so the caller
looses its exception.

type_call() with an exception set

with an assertion error if they are called with an exception set
(PyErr_Occurred()).

If these functions are called with an exception set, the exception may be
cleared and so the caller looses its exception.

Add also assertions to PyEval_CallObjectWithKeywords() and call_function() to
check if the function succeed with no exception set, or the function failed
with an exception set.

the last call to the step() method of a user function

PyObject_Repr() can removes the current exception. For example, module_repr()
calls PyErr_Clear() if calling loader.module_repr(mod) failed.

small integers (0 or 1 digit)

supports running only selected tests.  Patch by Zachary Ware.

supports running only selected tests.  Patch by Zachary Ware.

Original patch by Zachary Ware.