Use a better NaN test in _Py_HashDouble as well.

Objects/object.c

@@ -1025,9 +1025,12 @@ _Py_HashDouble(double v)
 	 * of mapping keys will turn out weird.
 	 */
 
+	if (!Py_IS_FINITE(v)) {
 		if (Py_IS_INFINITY(v))
-		/* can't convert to long int -- arbitrary */
-		v = v < 0 ? -271828.0 : 314159.0;
+			return v < 0 ? -271828 : 314159;
+		else
+			return 0;
+	}
 	fractpart = modf(v, &intpart);
 	if (fractpart == 0.0) {
 		/* This must return the same hash as an equal int or long. */