Dead code in `CALL_FUNCTION_EX` opcode handler

[sobolevn]

I am talking about these lines:

cpython/Python/ceval.c

Lines 4722 to 4734 in a36235d

	if (!PyDict_CheckExact(kwargs)) {
	PyObject *d = PyDict_New();
	if (d == NULL)
	goto error;
	if (_PyDict_MergeEx(d, kwargs, 2) < 0) {
	Py_DECREF(d);
	format_kwargs_error(tstate, SECOND(), kwargs);
	Py_DECREF(kwargs);
	goto error;
	}
	Py_DECREF(kwargs);
	kwargs = d;
	}

They are not ever called, because after #18141 all ** dict unpacking is handled in DICT_MERGE opcode.

This was found while working on #94808 but I think that it deserves a separate issue.

PR is on its way.

[mdboom]

Thanks for taking such an interest in coverage. This is very welcome (but I'll leave it to @markshannon to review the specific change in #96752).