entity_view('file') returns data nested in 'files' array, but should use entity type 'file'

Calling entity_view('file', $files) returns data in the following format:

array (
  'files' => 
  array (
  ),
)

But the resulting array *should* be keyed by entity type, which is 'file', not 'files':

array (
  'file' => 
  array (
  ),
)

We need to implement the same solution as the view callback for nodes which converts the result to the proper array.