PyErr_NewException now accepts a tuple of base classes as its

"base" parameter.

Doc/api/exceptions.tex

@@ -341,7 +341,8 @@ for each thread.
   The \member{__module__} attribute of the new class is set to the
   first part (up to the last dot) of the \var{name} argument, and the
   class name is set to the last part (after the last dot).  The
-  \var{base} argument can be used to specify an alternate base class.
+  \var{base} argument can be used to specify alternate base classes;
+  it can either be only one class or a tuple of classes.
   The \var{dict} argument can be used to specify a dictionary of class
   variables and methods.
 \end{cfuncdesc}

Misc/NEWS

@@ -12,6 +12,9 @@ What's New in Python 2.5 alpha 3?
 Core and builtins
 -----------------
 
+- PyErr_NewException now accepts a tuple of base classes as its
+  "base" parameter.
+
 - Patch #876206: function call speedup by retaining allocated frame
   objects.
 

Python/errors.c

@@ -527,6 +527,7 @@ PyErr_Format(PyObject *exception, const char *format, ...)
 }
 
 
+
 PyObject *
 PyErr_NewException(char *name, PyObject *base, PyObject *dict)
 {
@@ -559,9 +560,15 @@ PyErr_NewException(char *name, PyObject *base, PyObject *dict)
 	classname = PyString_FromString(dot+1);
 	if (classname == NULL)
 		goto failure;
-	bases = PyTuple_Pack(1, base);
-	if (bases == NULL)
-		goto failure;
+	if (PyTuple_Check(base)) {
+		bases = base;
+		/* INCREF as we create a new ref in the else branch */
+		Py_INCREF(bases);
+	} else {
+		bases = PyTuple_Pack(1, base);
+		if (bases == NULL)
+			goto failure;
+	}
 	result = PyClass_New(bases, dict, classname);
   failure:
 	Py_XDECREF(bases);