`$` not working on custom type when imported in other modules

[Yardanico]

For anyone curious for the exact source code, this seems to reproduce the 
problem:
    
    
    # lib.nim
    type
      Int_b* = int64
    
    func `$`*(i: Int_b): string =
      "somestring"
    
    
    Run
    
    
    # main.nim
    import lib
    
    var a: Int_b
    echo a
    
    
    Run

If you make `Int_b` a `distinct int64` \- it works, so I'm not 100% sure if 
this is a bug. I've tried searching existing issues, but nothing similar came 
up.