revert mrb_equal method

src/object.c

@@ -41,8 +41,11 @@ mrb_obj_equal(mrb_state *mrb, mrb_value v1, mrb_value v2)
 MRB_API mrb_bool
 mrb_equal(mrb_state *mrb, mrb_value obj1, mrb_value obj2)
 {
+  mrb_value result;
+
   if (mrb_obj_eq(mrb, obj1, obj2)) return TRUE;
-  if (mrb_test(mrb_funcall(mrb, obj1, "==", 1, obj2))) return TRUE;
+  result = mrb_funcall(mrb, obj1, "==", 1, obj2);
+  if (mrb_test(result)) return TRUE;
   return FALSE;
 }