non-idempotency with comments inside monad/listcomps

[lspitzner]

func =
  [ abc x y
  | _ <- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
         -- comment
  , x <- bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
  , y <- ccccccccccccccccccccccccccccccccccc
  ]

Each roundtrip through brittany will decrease the indentation of the comment.

Currently I cannot think of an easy fix on brittany's end for this because the ghc-exactprint interface is a bit unfortunate for this usecase. I have raised https://github.com/alanz/ghc-exactprint/issues/53.

[tfausak]

This seems like the opposite of #174 😆