Bitraversable is not derivable for These

Summary

I'm not sure whether this is technically a bug. But GeneralizedNewtypeDeriving can't derive Bitraversable for These. Which is a pity, because it's nice to re-use all the instances for These.

Steps to reproduce

$ cat Repro.hs
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
module Repro where
import Data.These
import Data.Bitraversable
import Data.Bifunctor
import Data.Bifoldable
newtype T a b = T (These a b) deriving (Bitraversable, Bifoldable, Bifunctor)

$ ghc Repro.hs
[1 of 1] Compiling Main             ( Repro.hs, Repro.o )

Repro.hs:6:41: error:
    • Couldn't match representation of type ‘f (These c d)’
                               with that of ‘f (T c d)’
        arising from the coercion of the method ‘bitraverse’
          from type ‘forall (f :: * -> *) a c b d.
                     Applicative f =>
                     (a -> f c) -> (b -> f d) -> These a b -> f (These c d)’
            to type ‘forall (f :: * -> *) a c b d.
                     Applicative f =>
                     (a -> f c) -> (b -> f d) -> T a b -> f (T c d)’
      NB: We cannot know what roles the parameters to ‘f’ have;
        we must assume that the role is nominal
    • When deriving the instance for (Bitraversable T)
  |
6 | newtype T a b = T (These a b) deriving (Bitraversable, Bifoldable, Bifunctor)
  |                                         ^^^^^^^^^^^^^
$ 

Expected behavior

Bifoldable and Bifunctor both work, so I'd expect Bitraversable to work too.

Environment

$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 8.6.5