Issue #16495: remove extraneous NULL encoding check from bytes_decode().

The NULL encoding check in bytes_decode() was unnecessary because this case
is already taken care of by the call to _Py_normalize_encoding() inside
PyUnicode_Decode().

Misc/NEWS

@@ -10,6 +10,8 @@ What's New in Python 3.4.0 Alpha 1?
 Core and Builtins
 -----------------
 
+- Issue #16495: Remove extraneous NULL encoding check from bytes_decode().
+
 - Issue #16619: Create NameConstant AST class to represent None, True, and False
   literals. As a result, these constants are never loaded at runtime from
   builtins.

Objects/bytesobject.c

@@ -2236,8 +2236,6 @@ bytes_decode(PyObject *self, PyObject *args, PyObject *kwargs)
 
     if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|ss:decode", kwlist, &encoding, &errors))
         return NULL;
-    if (encoding == NULL)
-        encoding = PyUnicode_GetDefaultEncoding();
     return PyUnicode_FromEncodedObject(self, encoding, errors);
 }