Fix SF bug# 676155, RuntimeWarning with tp_compare

Check return value of PyLong_AsDouble(), it can return an error.
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index f7e652d..55ea8d2 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -186,6 +186,7 @@
             def __coerce__(self, other):
                 raise ValueError
         self.assertRaises(ValueError, coerce, 42, BadNumber())
+        self.assertRaises(OverflowError, coerce, 0.5, int("12345" * 1000))
 
     def test_compile(self):
         compile('print 1\n', '', 'exec')