Record updates with RDP are not idempotent

```haskell
{-# OPTIONS_GHC -fplugin=RecordDotPreprocessor #-}

a =
  def{ N.k = g
     }
```

Invoking ormolu-0.1.4.1 results in:

```haskell
{-# OPTIONS_GHC -fplugin=RecordDotPreprocessor #-}

a =
  def
    { N.k = g
    }
```

Invoking ormolu-0.1.4.1 again results in:

```haskell
{-# OPTIONS_GHC -fplugin=RecordDotPreprocessor #-}

a =
  def{N.k = g
     }
```