BUG: Regression in .get(None) from 0.12 (GH5652)
closes #5652

This is just back-compat, right? because the correct thing here is... debatable.
 yep, though the user can easily get the 'correct' behavior by just regular indexing, e.g. `meat[None]` will raise
 `get` as in `dict.get(NoSuchKey)`. Right.
