I don't think this a bug, but a feature request. I therefore think hackers would be more appropriate.
I don't see how an additional syntax to modify the constraint should help.
If I'd want to fix this, I'd try to teach the detach partition code about self referencing foreign keys. It seems to me like that would be the cleanest solution, because the user doesn't need to care about this at all.
I don't think, I'll spend time on this in the near future though.
