Issue #5175: PyLong_AsUnsignedLongLong now raises OverflowError for
negative arguments.  Previously, it raised TypeError.

Thanks Lisandro Dalcin.
diff --git a/Objects/longobject.c b/Objects/longobject.c
index fdbda6b..ddfa72b 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -557,7 +557,7 @@
 	if (Py_SIZE(v) < 0) {
 		ndigits = -(Py_SIZE(v));
 		if (!is_signed) {
-			PyErr_SetString(PyExc_TypeError,
+			PyErr_SetString(PyExc_OverflowError,
 				"can't convert negative long to unsigned");
 			return -1;
 		}