RepeatingEnumValueException when parsing enum with hex values

In my .thrift, I have :

```
enum TrueFalse
{
    False = 0,
    True = 1,
    Unknown = 0x7FFFFFFF
}
```

I get a FileParseException caused by RepeatingEnumValueException: Repeating enum value in TrueFalse: 1.  Replacing the hex value with 2147483647 (Int.MaxValue) results in no error.  Is this a bug?
